I won, I won…

Well…unofficially anyway.

Airfield shooting club hosted an “as issued military rifle” match on Saturday.

Not to pick nits, but they did allow a couple of AR style rifle entries, which technically aren’t “as issued military rifles” but it was just a fun match anyway so nobody complained.

I hadn’t been to the range in quite a while.  Considering that I still have half a case or so of .30-06 and the entry fee for club members was only $5, I figured I could spare that and maybe the same amount on gas to participate.

I loaded my M1 Garand (which is too dangerous for us lowly civilians to own, don’t you know…just ask the Brady Campaign…why would anyone want one of those military style rifles anyway?  They’re only good for killing people…or something.  But I digress…as usual) and assorted other shooting paraphernalia onto the bike and hit the range for the first time in a while.

I shot in the third relay.  Another shooter in the second relay was using a Krag carbine.  I’ve seen them at gun shows and places like that, but I’ve never actually seen anyone shooting one…and BOY was he shooting his.  I knew he was going to be a challenge to beat.

I shot pretty well.  I have to admit after shooting my National Match AR for a while, with it’s two stage, four and a half pound trigger, the Garand felt like trying  pull a truck with my trigger finger.   The Garand really does have a good trigger for a stock service rifle…no creep, crisp letoff, but I’d guess the pull weight is around 7 or 8 pounds.  Might be time for a trigger job.

As an added excuse, I lost my reading glasses right before it was my turn to shoot, so I was having a hard time focusing on the front sight.  Interestingly, I realized that my vision is such that, when prone, My eyes are just enough closer to the sights to make the front too close to focus on…but when standing off-hand, it’s a couple of inches farther from my eye, which was enough to make it come clearly into focus when shooting from that position.  I was actually very pleased with my off-hand shooting for the first time in a long time.

Anyway, overall, I was pretty pleased with my shooting…could have been better, but didn’t suck…and after talking to Mr. Krag (also known as Chuck) while scoring my targets, he told me that we had tied on score but that I had beat him in Xs.

The official results were posted today and he was right…except they didn’t post the Xs in the results.  I don’t know why.

So I suppose officially we tied with scores of 261, but I know that he told me he only got 2 Xs to my 3, so I’m declaring myself the unofficial winner.

Not that it’s THAT important to me, but hey, bragging rights are bragging rights…especially because Chuck is a retired Marine.

Go Navy.

Rifle Matches Wrapup

I got busy right after the matches ended, first working on my Son’s graduation gift, and then on a project for  VCDL, and I never got my final wrap up post from the Atlantic Fleet and All Navy Rifle and Pistol matches written.

I ended up not doing as well as I had hoped, but was improving by the end of the All Navy match so I still have hope for the future.

One thing I was very happy with was my rifle.  I didn’t have a single failure of any kind, my actual sight settings were as close to exact as I could hope for (What I mean is, when I put in 8 clicks of adjustment, I got two minutes of angle of change in POI.   What that tells me is that the sight adjustments are calibrated correctly and are accurate), it was putting the holes in the targets right where the sights were aligned (I’ve just gotta get better at aligning the sights with the X in the middle of the target), it was very easy to clean (for an AR) with very little copper fouling.  I’m just ecstatic with how it performed.

One thing that’s interesting is that my other AR…the one for which I purchased a pre-assembled upper that was built by a reputable company…is less reliable than the one I completely put together on my own.

I don’t know why yet, but if the Del-ton upper on my M4 style rifle is the least bit dirty, it starts having chambering and feeding issues.  I haven’t messed with it yet to figure out what’s going on, but I want to change the configuration of it anyway, so I’ll be completely disassembling the upper here in a while and figuring out what’s up with that.

But I digress.

My lessons learned from this match:  I need to practice more.  Most of my problems were related to inconsistency in my positions, and the fact that getting into position isn’t as natural an act as it should be.  The only thing that can fix that is practice.

My off-hand, as usual, left a lot to be desired.  I was calling my shots virtually unerringly…the shots were going where the sights were aligned, but I wasn’t getting the trigger to break when the sights were aligned at the right place.  I need LOTS more dry fire practice in off-hand.

On the plus side, as I mentioned in past posts, I was very pleased with my wind-reading and adjusting.  I think I handled the weird, swirling and shifting winds of Dam Neck as well as anyone and better than most.  By the end of the All Navy match, I had more than a couple people asking me what I thought about the winds before deciding on their final adjustments.  That’s gratifying.

One of the most frustrating things for the better shooters about the rapid fire stages is misreading the wind by just a little bit and making a nice tight group…all in the 7 and 8 ring off to the right or left.   My problem isn’t getting the adjustments right.  Every one of my rapid fire groups was centered perfectly…my groups were just too big because I wasn’t consistent enough from shot to shot.  I basically dance all around the X ring.

So, finally, how did I do?

Overall, about normal.  By the final match of the second week, the All Navy EIC match, I actually fulfilled my goal of moving up in the standings, but leading up to that, I pretty much was solidly in the middle of the pack every time.

How I did in that final match, however, did a lot for boosting my confidence and encouraging me to keep working and do better next time.

Here are my final scores and placing.

Off Hand
Slow 200yd
Rapid 200yd
Rapid 300yd
Slow 500yd
Total Place
Fleet Forces Command Atlantic Individual Rifle
78-0x 86-1x 87-0x 189-3x 440-4x 78 of 148
Fleet Forces Command Atlantic EIC Rifle
83-0x 83-1x 90-1x 180-2x 436-4x 73 of 133
All Navy (East) Individual Rifle
82-0x 94-1x 90-0x 193-6x 459-7x 49 of 118
All Navy (East) EIC Rifle
82-0x 91-0x 94-1x 185-3x 452-4x 21 of 70

So, as you can see, not terrible, but not great and pretty consistently so.

I did improve my scores slightly from week 1 to week 2 which is encouraging, and improved my overall placement relative to the other shooters pretty steadily as well.

The reason I moved up in the rankings on the All Navy EIC match, even though my score was not as good as the Individual Match, is because the weather conditions were much more challenging on EIC day than during the Individual rifle match.  Because I adapted better to the…um…interesting…wind conditions, I did better with respect to the other shooters, even though my score actually went down slightly.   During both weeks, the winds on EIC day were worse than during the Individual match.  I actually shot better than most at 500 yards in the EIC All-navy match, which helped make up for my typically poor performance in off-hand.

Anyway, the bottom line is that I need to practice more, both at home practicing my positions and dry-firing, and at the range actually putting lead downrange.

I’ve found out that one of the gun clubs in the area has been doing monthly high powered rifle matches at Blackwater in North Carolina, so I’m going to start competing in those as often as I can.  Shooting a regulation match once every three or four years just isn’t cutting it, even if I do shoot reduced range 100 yard matches in between.  There just is no substitute for actually going to a real rifle range and shooting at 500 or 600 yards.

I just wish there were more rifle ranges around here to do that at.   Every time I drive by any of the many golf courses in this area, my immediate thought is “what a shameful waste of a perfectly good rifle range…”

Anyway, now that I’ve gotten that off my chest, I’ll stop blathering on and boring you about the matches…at least until next year.

Promise kept

I promised you a picture of the targets from the 500 yard line.

I’m going to go one better.

I already showed you what the targets look like from 200 yards, but here’s a reminder of that view.

This is what they look like from the 300 yard line.

It’s the same size target as the 200 yard target, but at 200 yards, the black only covers out to the 9 ring.  On the 300 yard target, the black covers the 8 ring as well.

The black and white ammo cans in the foreground mark the 200 yard line, where the first picture was taken from.

Sorry about the tilt.  I don’t know why, but I sometimes have issues holding the camera level when taking pictures.  I never seem to notice it until I get home.  I usually use Gimp to rotate them back to level but I didn’t bother this time.  Too tired.

And here’s the view from 500 yards.

Again, the ammo cans in the foreground mark the 300 yard line, where the last picture was taken from.

The most important thing about shooting long distance, whether with open sights or a scope, is knowing your rifle’s sight/optics settings and your ammo’s ballistic characteristics.

If you don’t know the correct sight settings to at least get you on paper, or have no idea how much the bullet is going to drop over the distance you’re firing at, there is no way you’re ever going to get hits on target.

After you get that worked out, it’s just a matter of reading the weather conditions, adjusting your sights accordingly, and then employing basic shooting skills:  Proper position, proper use of the sling to stabilize your hold, proper hold, proper sight alignment and sight picture, proper breath control, proper trigger control and practice, practice, practice.

The black appears as nothing more than a speck using iron sights at these distances.  Consistency is the key.  Every aspect of each shot has to be as close as possible to exactly the same as every other shot in order to make good groups.  At this distance, the tiniest difference in your sight alignment, sight picture, hold, etc can send a shot a foot, or even a couple of feet, away from your previous shot.  Even your heartbeat can effect your sight alignment and, therefore, change your point of impact on the target.

As daunting and intimidating as that may sound, the fact is that anyone physically capable of performing the necessary tasks can learn to do it.  Give it a try sometime.  The old hands will help you out, explain the ropes and get you on paper in no time.

Here’s a great article from the US Army Marksmanship Unit (posted on the CMP web site) about what you need to get started in High Powered Rifle shooting.  Although there’s the potential to spend thousands of dollars on fancy equipment, it isn’t necessary to get started and you probably already have most, if not all, of what you need.

Incidentally, that article is one of a series done by the USAMU about High Powered Rifle Shooting.  The articles are a great resource for someone who wants to learn more about the tricks and techniques of the discipline.

It is challenging and takes a lot of dedication and hard work to become one of the top contenders, but even if you don’t aspire to that level, it is also a great way to build your skills as a rifleman and learn more about precision shooting at long ranges.

That’s enough for today.  EIC pistol is tomorrow and that’s the last day of competition for me.   They are having another 500 yard “fun” rifle match later in the week, but I couldn’t get that much time off work so I’ll have to miss it.  I’d have really liked one more opportunity to shoot at 500 (that’s my favorite stage of the matches), but it was not to be this time.

After it’s all over and when time allows, I’ll do one more “wrap-up” post about the matches, how I did, lessons learned and my plans for the future.

I’m Exhausted…

…but I’ve just gotta share.

Today was the 500 yard stage of the Individual rifle match and the President’s 100 pistol match.

We rushed to get it done because it was threatening to storm all day.  They wanted to try to get in as much as possible before the storm, so we were on the run all day.  The storm never materialized so we got everything done, but finished really early…and really tired.

Anyway, that’s not what I wanted to share.

I shot a personal best in the 500 yard stage today.

For those unfamiliar with High Powered Rifle matches, in a standard National Match course of fire, the long line stage is 20 shots in 20 minutes slow fire from the prone position.  The maximum score you can get is 200-20X.  The 10 ring is 12 inches in diameter and the X-ring (still counts as a 10, but also scores an X) is 6 inches in diameter. 

I shot a 193-6X

I shot two 8’s and three 9’s.  The remaining 15 out of 20 shots were within a 12″ circle and 6 of those were within a 6″ circle.

At 500 yards.

With iron sights.

For the really good high powered rifle shooters (like Robert Langham, for example), that’s no big deal, but for me that was a significant achievement.  Success is a great motivator to keep one working toward improvement.

Now I’ve gotta get some rest.  I’m beat.

National Match AR Range Report

Now that the series of posts on assembly for my National Match AR-15 build project is done, it stands to reason that I need to let everyone patient enough to slog through all those very detailed and meticulous posts know how she shoots.

First a little background. I had heard that new match barrels need to be “broken in” so I did some research on that subject before beginning. It seems that there are as many opinions on that as there are on every other aspect of guns and shooting.

Some recommend using a brush during break-in.
Some recommend not using a brush during break-in.
Some recommend a set number of rounds in a regimen for break-in.
Some recommend shooting only until fouling is reduced.
Most recommend somewhere between 20 and 30 rounds for break-in.
I had one “know it all” type at a local gun range tell me that a minimum of 300 rounds is required for proper barrel break in.
And at least one fairly well known industry professional is on record as saying that “break-in” is unnecessary, does more harm than good and is only recommended by barrel makers to get you to shoot your barrel out faster than you would otherwise.

In summary, after all my research, I still don’t know what the “proper” barrel break-in procedure is or even if there really is one.


Well, I couldn’t find any match ammo to shoot so I was going to have to settle for cheap range ammo to start out with anyway, so I decided to go ahead and do at least some break in.

I went to Camp Allen Weapons range during a time that I thought wouldn’t be too busy (I was right…only one other guy in the bay with me and only for a short time), set up my cleaning station.

Set up my shooting position.

And went to town.

Here are my first five shots, stopping and cleaning between each shot (yes, I used a brush).

I must say, for cheap 55 grain range ammo, shooting one round at a time, getting up, cleaning and then shooting the next round, I couldn’t be happier with that group.

I was using a 6 o’clock hold for the large center diamond, which put me 7 inches low and about 3 inches left.

Unfortunately, I forgot the tools I needed to adjust the FSB. I tried the “bullet tip” trick to adjust the front sight post down to bring the shots up a little, but after a couple of turns, it was obvious that I was going to tear the front sight post up too much if I kept going with that.

After adjusting the front sight post a little, I didn’t know where I was going to be, so I needed to shoot another group to check elevation, but I could at least try to adjust the windage. Let’s see…1MOA at 25 yards is 1/4 inch. I’m shooting 3″ left so I need to move the point of impact 12 MOA right.

One very important aspect of a match rifle is how accurate the click adjustments are on the sights. You don’t get a chance to verify adjustments during a match so you need to know that when you dial in a certain adjustment, that’s what you’re going to get on the Point of impact.

So, with 1/4 MOA sights, a 12 MOA adjustment is 48 clicks. Whew…that’s barely in the adjustment range.

OK…now that I’ve made my first adjustment, it’s time for another 5 shot group. After cleaning between each shot for the first 5 shots, I’m really not seeing any significant copper fouling. A little to be sure, but nothing significant. I think it’s safe to start shooting 5 shots between cleaning.

The second 5 shot group was almost perfectly centered right to left. That tells me that the windage adjustments are accuarate and I can trust my math when making adjustments. That’s great news!

I was still about 26 MOA low though. I wasn’t going to futz with the front post any more without the proper tools, so…I need to move my POI 26 MOA up, that’s 104 clicks.

After cleaning, I shot another 5 shot group: almost exactly where I expected it. Grouped just a little high but almost perfect. OUT STANDING.

I decided to shoot one more group on a clean target to finish off the box of 20 and “for record”. I cleaned one more time, set up…and this is what I ended up with.

Out freaking standing.

I’d say about a 3/4″ group…about 3 MOA. Three out of the 5 cloverleafed.

Using cheap ammo from nothing more than a rudimentary rest and without even having the sights dialed completely in yet.

I’ll take it.

That was the day that I got my gunny body art by the way.

I took her to the Airfield shooting club last weekend and put another 20 rounds downrange and got the FSB windage at least in the ballpark, and I cranked the front sight post down 4 or 5 turns to get the point of impact up a bit. I didn’t take pictures that day because I was just too tired after being out there all day.

Today I went back to the indoor range to verify my FSB adjustments.

Still gonna need some fine tuning after getting the right ammo, but it’s really starting to come together.

here was the last group of 5 (out of another box of 20) that I shot today.

This was with 50 clicks (12.5 MOA) up and the windage dial zeroed.

Looks like I still need to move the FSB about 2 MOA right and the sight post maybe another turn down (Front sight adjustments are opposite of where you want the POI to move, rear sight adjustments are the same direction you want the POI to move).

But the main thing I’m happy about was the groups I was getting tonight.

That one looks to be slightly less than 1/2 an inch.

Call it .45 inches from center to center of the largest spread. I used a box to mark it to make sure the lines were straight down.

At 25 yards, that’s about 1.8 MOA.

I know I’m repeating myself…but…just wow…

Less than 2 MOA accuracy already with crappy ammo that’s really too light for the barrel twist rate from a makeshift rest and without even having the sights all the way dialed in yet.

I think I’ve achieved everything I’d hoped for when I first started contemplating this project.

I’m confident that, with good ammo and from a proper, stable bench rest, I’ll be able to get sub-MOA groups out of this rifle.

I’m officially calling this project a WIN!.

NM Rifle Build Part 10

In Part 1, we introduced the series and talked about tools.
In Part 2, we installed the magazine catch and trigger guard.
In Part 3, we installed and adjusted the Jewell Match trigger.
In Part 4, we installed the safety selector, pistol grip and bolt catch.
in Part 5, we installed the pivot pin, recoil buffer components and buttstock.
In Part 6, we installed the forward assist and the ejection port cover.
In Part 7, we installed the delta ring and barrel.
In Part 8, we installed the free float tube and front sight base.
In Part 9, we installed the handguards, flash hider, bolt carrier group and mated the receivers.

This is the final of the assembly posts. I didn’t specifically try to keep the assembly posts to an even 10, but it is convenient that it worked out that way.

The Front Sight base that came with my DPMS barrel actually had a sight post installed out of the box. It really would have been an acceptable front sight for a NM rifle as it is thinner than the standard A2 Sight, however, the Rock River NM rear sight I bought also came with an actual National match front sight post that I wanted to install.


What’s the difference? I’m glad you asked.

I actually shouldn’t have labeled the one that came on the rifle as “standard” because the standard A2 sight post is a square .070″ post.

The one that came stock in the DPMS sight base was a square post, but significantly smaller than .070″…probably .050″ but I didn’t measure.

The National match post (shown in two different views, side and end-on) is not square, but rectangular. Its also beveled toward the front and is theoretically precision machined to create sharp, distinct edges. The shape is to cut glare and make a nice, clean edged sight picture even at long range.

The only disadvantage to the NM style sight post is that it is designed to be oriented in a specific way. That means when you adjust it, you have to turn it in or out a full turn to keep it oriented correctly, whereas with a square post, you can turn it in quarter turn increments. In other words, the standard front post has four times the adjustment sensitivity of the NM post.

Realistically, though, you don’t adjust the front post for a perfect zero anyway…the front post is only adjusted to get your rear sight in the adjustment range you want…so that isn’t really much of a disadvantage at all.

Installation is the same no matter which type of sight post you choose.

The front sight post assembly consists of three parts (other than the sight base, of course).

The post itself, the detent spring and the detent.

Some match shooters include a set screw with the same diameter and thread pitch as the sight post shaft.

What they do is tap the front sight post hole in the FSB all the way through, and then install the set screw through the bottom. After adjusting the front sight, they tighten the set screw up against it to lock it into place and prevent any movement at all.

I may do that at some point, but I didn’t do it during this assembly process.

The front sight base has two holes in the top. The smaller, front hole is for the detent and the rear, larger, threaded hole is for the sight post.

The detent spring goes into the front hole.

then the detent goes over top of that, with the “nub” pointing up.

Then the post is screwed into the threaded hole.

When the post is screwed down far enough, you’ll have to push the detent down to continue screwing in the sight post.

They make a tool for this, but I don’t have one yet. I never thought I needed it, but after having screwed with the front sight as much as I have lately, I can definitely see that it would make my life easier. I plan to order one from MidwayUSA when I order the sling…maybe today: It’s payday…just gotta pay the bills and see where I stand financially to decide whether I can afford it this time or have to wait for my next check.

It’s hard to see in this picture, but when installed correctly, the National Match front post will be oriented so that the ramped top edge is angled down toward the muzzle end.

It will have to be adjusted to get the zero point of the rear sight where you want it, just remember to adjust the National Match front post in full turns to keep it oriented correctly.

The Rock River Arms National Match rear sight is outwardly almost identical to the standard sight, but there are some differences there as well.

The most obvious difference is that the aperture has a “hood” that is designed to cut down on glare.

The aperture inside the hood is significantly smaller than a standard aperture as well.

The standard A2 sight comes with two apertures, a larger one for close in or low light work and a smaller one for distance. I don’t know the sizes, but I know for sure that they are significantly larger than the .040″ match aperture.

The smaller aperture is not suitable for a defensive or combat rifle because it reduces your field of view to almost zero, but it is great for match shooters because the small aperture increases depth of field (helps keep the target more in focus, even when concentrating on the front sight) and makes it easier to focus clearly on the front sight…as well as just having a smaller area in which to center the front sight post, which can help cut down on tiny errors that can make dramatic differences in impact point at 600 yards.

Another physical difference is the elevation ring. On a standard A2, the elevation knob is actually two parts, the bottom elevation knob, and the top elevation index. They are held together by a set screw. Turning the elevation knob changes the elevation. Loosening the set screw and turning the elevation index, just moves the range index marks to match the sights setting with the effective range that the sight is set at.

The Elevation knob that came with my Rock River National Match sight is a single, solid piece. There are no range markings on the elevation knob at all.

Another obvious feature is that this single elevation knob can be used for 1/2 MOA or 1/4 MOA adjustments, depending on how it’s installed in the rifle. On one side of the knob are detent dimples spaced for 1/2 MOA adjustments.

On the flip side, the dimples are closer together and there are twice as many of them…for 1/4 MOA adjustment clicks.

The final difference is not visible at all unless the windage adjustment knob is removed. The windage adjustments are also set for 1/4 MOA adjustments.

Well made National Match sights tend to be manufactured and calibrated with greater precision than standard sights as well. On National Match sights, one click should be very close to exactly 1/4 MOA (calibrated for a 20″ barrel), whereas standard sights may be in the ballpark, but not necessarily exact.

The RRA rear sight assembly came pre-assembled as much as possible.

The windage knob, ball bearing and spring were already installed, as were the leaf spring and aperture.

The only parts that were loose were the ones that had to be mated with the upper as the sight was installed. Those were the elevation knob, the sight body and elevation detent ball bearings and detent ball bearing springs, the elevation spring, and the rear sight roll pin.

First, drop one of the detent ball bearing springs into the hole in the right front face of the sight base.

It’s a good idea to put a dab of gun grease on top of the spring. That will help hold the ball bearing in place as the sight base is installed.

Then drop the detent ball bearing into the hole on top of the spring and grease.

Next, drop the other detent spring into the lower receiver into the small hole toward the front of the well that the elevation knob goes into.

And put the remaining ball bearing into the hole and on top of the spring.

Next, slip the elevation knob into it’s well in the receiver. It should push the ball bearing down out of the way as it goes in. When properly positioned, the ball bearing will be pressed into one of the elevation adjustment “dimples” on the bottom of the elevation knob, snapping it into place.

Be sure to put the correct side down for the sensitivity of elevation adjustments you want. Since the detent ball is on the bottom, that’s the side of the elevation knob that will determine whether you get 1/2 MOA or 1/4 MOA clicks. In this case I want 1/4 MOA adjustments so I installed the elevation knob with the side up that has the lesser number of dimples.

With the elevation knob installed and the threaded hole of the knob centered in the hole in the reciever, CAREFULLY lower the sight body so that the threaded post goes through the hole in the receiver and mates with the threads of the elevation knob.

Be careful to press the sight body detent ball bearing against the rear flat surface of the carry handle to prevent it from dislodging and falling out of the sight base.

Hopefully, the grease will help hold it in place.

Carefully turn the elevation knob counter-clockwise (when looking at it from the top) to screw the sight base post down into the receiver. You should be able to clearly feel the “clicks” as the elevation knob dimples pass over the detent ball bearing. Be sure to start out slowly. You’ll be pressing the sight body against the spring tension of the sight body detent ball bearing spring, which will be trying to cant the sight body as it goes in. Be careful not to cross-thread the elevation knob as you get it started.

Screw the sight body all the way to the bottom.

At this point, if you haven’t done so already, remove the bolt carrier and charging handle, then flip the receiver upside down.

Inside the receiver, you will be able to see the hole in the bottom of the sight base post. Insert the elevation spring into this hole.

Here’s where things got a little tricky. You have to be able to compress the elevation spring up into the sight body so that the sight pin doesn’t pass through the spring, but under it (over it in this picture because the receiver is upside down).

The problem is that if you press the spring down with something solid like a pin punch, its in the way and you can’t install the pin.

You need something to push the spring down, but won’t interfere with the pin passing through the receiver and sight base post.

They do sell an A2 sight installation tool just for this purpose, but I felt the asking price was a bit high for what it was, I decided to wing it. I made a sight tool out of a popsicle stick.

I used a round jewelers file to file a notch in the top of the popsicle stick large enough for the pin to pass through.

Then I filed the sides down so that it would fit in the hole in the sight base post.

I ended up with a makeshift tool that looked like this.

Not perfectly straight, but close enough for government work.

I used the popsicle stick, aligned fore and aft so that the notch in the top was aligned with the side-to-side pin hole, to catch the edges of the elevation spring and compress it into the sight base.

Once I got the spring down far enough, I used a pin punch to pass over the spring and temporarily hold it in place.

The spring should be captured completely by the pin punch. You don’t want the punch passing through any of the spring loops.

At that point, it was just a matter of driving the sight base pin in and pushing the pin punch out as it went.

And that’s it.

As usual, my explanations were more complicated than the installation procedure.

The last thing to install to make a complete, operational rifle is the magazine.

I purchased two, mil-standard 20 round magazines from MidwayUSA. The magazines are made by C-products, which I’ve heard good things about, but I only bought two for now so I can test them out and make sure they function well before buying more.

I did have one failure to feed and I’ve had the bolt fail to lock back on an empty mag a couple of times, so the jury is still out on these.

Right now, I’m still using cheapo PMC 55 grain ball ammo…which I’ve heard of people having feeding problems with. I’ll know more after I get some good match ammo and try it.

So, over the course of maybe 6 hours over two days, and ten blog posts we went from this:

To this:

Of course, this won’t be the last post about my new National Match AR, I’ve still got a few accessories to add (buttstock weights, possibly handguard weights, and sling), range reports to do, sight adjustments and zeroing, etc…but if all you were here for was the actual assembly process, this is the last of that series.

Click here for first range report

As usual, it took orders of magnitude longer to write the posts documenting the work than it did to actually perform the work…even with staging and taking pictures during the process.

As I mentioned before, my son and I did this assembly (actually, he did most of the work because he wanted the experience…I just took pictures and provided a helping hand from time to time), in about 5 hours on Saturday and about another hour or so on Sunday. We could have done it in half that had we not been worrying about setting up, staging and taking pictures and, now that we’ve done it once and know what we’re doing, could probably come close to cutting that in half again. That’s the beauty of the AR platform: it’s so modular and interchangeable that virtually anyone can assemble, customize and maintain them and the sheer variety of parts and customizations available is staggering.

I’ve already had a couple of comments on posts in this series from people who found them useful and I really appreciate that. Helping people by sharing my experiences is what these posts are all about so, if you find them useful, please let me know in the comments so I’ll be motivated to keep doing them as I experiment, practice and learn more about this gunsmithing stuff.

And, finally, to sum it all up, one more look at the cheesy little video I posted before starting this assembly post series:

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NM Rifle Build Part 9

In Part 1, we introduced the series and talked about tools.
In Part 2, we installed the magazine catch and trigger guard.
In Part 3, we installed and adjusted the Jewell Match trigger.
In Part 4, we installed the safety selector, pistol grip and bolt catch.
in Part 5, we installed the pivot pin, recoil buffer components and buttstock.
In Part 6, we installed the forward assist and the ejection port cover.
In Part 7, we installed the delta ring and barrel.
In Part 8, we installed the free float tube and front sight base.

This time, we’re going to install the handguards and flash hider, assemble and install the bolt carrier group, and mate the upper and lower for the first time.

As usual, click pix to make bigger

The handguards are pretty simple. The only difference between the float tube handguards and standard is that the heat shields are removed, and some of the plastic around the front end is trimmed away to make them fit over the float tube. Other than that they are stock handguards and go on the same way that stock handguards do.

Slip the front tabs of the top handguard into the handguard retainer on the front of the float tube.

Pull back on the delta ring.

Try to slip the back of the handguard into the delta ring.


Pull back on the delta ring HARDER, finally get it to pop in.

They actually make a tool for prying the delta ring back but I always thought $29.99 was a bit steep for a piece of bent thin metal rod so I’ve never considered buying one.

Anyway, repeat with the bottom handguard. Make sure they snap together completely after getting the bottom one into the delta ring. Make sure the delta ring is as far forward as it will go, securing the handguards to the float tube.

The last part of the barrel installation is the flash hider.

There are actually two types of washers that can be used for the flash hider. I chose the peel washer. it is basically a washer made up of thin laminated layers of metal. You can peel off layers to make it exactly the thickness you need.

The other style is the “crush” washer. As its name implies, it crushes as you tighten the flash hider which adjusts the thickness dynamically.

I chose the peel washer becaused it seemed to me that the setup would be more consistent and stable for accuracy. Don’t know if that’s right or not, but seemed that way to me.

What we’re trying to accomplish is to get the flash hider torqued to 15 to 20 pound feet with the ports pointing up and the closed side down.

The first time I put it on, with the full peel washer underneath it, when hand-tight, the ports were canted to the right (as we’re looking at it in the picture). To get the ports indexed properly, the flash hider would have to be turned almost another full rotation. No way that’s going to be right.

The best way I found to peel layers off was with a utility knife. The blade was thin enough to get between the layers easily and with good control, but not so thin that I was worried about it breaking.

Find the thickness that you want to peel away and place the blade there.

Then tap it gently with a small hammer to get it started.

Once the layers have started peeling apart, you can just push the blade through to finish it.

After peeling off a layer and trying it, and peeling off a layer and trying it, I finally ended up with getting it about where I wanted it.

As soon as you think it’s in the right ballpark, try torquing it. If you start to go over 20 pound feet, peel another layer and try it again.

20 pound feet really isn’t much torque so it shouldn’t have to turn far to be torqued correctly.

Conveniently, the AR-15 multi tool has a section made for tightening the flash hider.

Also conveniently, it happens to be oriented so it’s easy to tell when the flash hider is indexed correctly…you turn the tool until it is horizontal and the flash hider is oriented properly.

The hole for the torque wrench is in a strange place in relation to the flash hider wrench part, but as long as you keep the torque wrench at a 90 degree angle with the lever point, it will work fine…or at least it did with my torque wrench. By the way, the extension length for this operation was exactly the same as for the barrel nut torquing: 1.5 inches. That means the correction formula was the same. I actually ended up with an indicated torque of 13 to 18 pound feet to get an actual torque of 15 to 20.

The procedure for torquing is the same as for the barrel nut. Torque to the minimum. If the flash hider still isn’t indexed correctly, set the torque wrench to the maximum and continue turning until the max is reached or the flash hider is indexed correctly, whichever comes first. If the max torque is reached first, you need to take it back off, peel another layer from the peel washer and try again.

The next thing on the list is the Bolt Carrier Group.

The BCG consists of the bolt carrier itself which should include the already installed key and screws. If the key isn’t installed, this is a problem because the screws have to be staked. If you don’t have the staking tool, just be sure to order one with the key already installed.

Also included is the bolt assembly. Also should come pre-assembled, but includes the ejector, ejector spring and ejector pin, the extractor, extractor spring and extractor pin, and the bolt rings.

Next you have the charging handle. This is actually not technically a part of the BCG, but is an integral part of the BCG installation so it’s included here. It consists of the handle, the latch, the latch spring and the latch pin.

Finally, the firing pin, the cam pin and the firing pin retaining pin.

The first thing to do is put the bolt into the bolt carrier, and the first step of that is to make sure the gaps in the bolt rings aren’t aligned.

Sort of like piston rings on an engine piston…the gaps need to be staggered.

The bolt orientation in the carrier is critical as well. The ejector is just a round pin in the face of the bolt. The extractor is a wide hook that extends past the edge of the bolt face.

The extractor hooks on the rim of the cartridge as it is pushed into the chamber. The ejector is compressed under the cartridge base.

After firing, as the bolt moves away from the chamber, the extractor pulls the rim of the empty case, and thereby the rest of the case, to the rear and out of the chamber. Meanwhile, the ejector is pushing against the opposite side of the base of the shell casing under spring tension. As the casing clears the chamber and moves into the ejection port, the ejector pushes the shell casing away from the bolt face, out from under the extractor and out of the ejection port.

If the bolt isn’t in the right way, the ejector and extractor are on the wrong sides. that means that the shell casing will try to eject out the wrong side of the receiver…the side that doesn’t have an ejection port for it to pass through. As you can imagine, this doesn’t work very well and you end up with the empty case jammed in the rifle after your first shot. Basically, it turns your fancy AR into a very expensive single shot rifle.

So, insert the back of the bolt into the front of the carrier and push it in as far as it will go, ensuring that the ejector is to the left, and the extractor is to the right. (opposite in this picture because we’re looking at it from the front).

Next is the cam pin.

The cam pin is what rotates the bolt in the carrier to lock it in the breech when the bolt is closed, and to unlock it so it will open after firing.

There is a large hole that passes through the bolt from top to bottom.

Line that hole up with the elongated hole in the top of the bolt carrier.

Rotate the cam pin so that the hole in it is crosswise to the bolt carrier.

Then insert it into the bolt carrier and bolt through the elongated hole in the carrier.

If you have the cam pin turned the wrong way, it simply won’t go in because the bolt carrier key will be in the way.

Once the cam pin is fully inserted into the bolt and bolt carrier, turn it a quarter turn (either direction…it doesn’t matter).

Now, with the hourglass shaped part to the rear and the pointy end toward the front of the bolt carrier, insert the firing pin through the bolt carrier and bolt from the back.

With the firing pin as far forward as it will go, insert the firing pin retaining pin through the recessed hole in the left side of the bolt carrier and seat it fully.

The “eye” of the firing pin retaining pin should fit down into the recess in the bolt carrier.

OK, now the BCG is together.

The next step is to put the charging handle into the receiver. The charging handle travels along a channel in the top of the receiver. The channel in the receiver has cutouts that the rails in the charging handle will slip through.

The hollow side of the charging handle should be pointing down…it’s up in this picture because the receiver and charging handle are upside down to make them easier to see.

Basically, put the charging handle in the receiver and, while pressing it against the top of the receiver, slowly start pushing it in. When you reach the right spot, the charging handle will slip through the gaps and pop up into the channel it rides in.

Next, make sure the bolt is fully extended from the bolt carrier. The cam pin should be directly under the bolt carrier key and if you pull on the bolt while holding the bolt carrier, it shouldn’t come out any farther.

Now, with bolt face toward the front of the reciever, pull the charging handle out just enough that the bolt carrier key will slip up into the hollow bottom of the charging handle.

Then push the bolt carrier and the charging handle the rest of the way into the receiver together.

If the ejection port cover is closed, it will pop open as the bolt carrier passes it.

When fully inserted, the bolt will rotate and lock into the breech and the charging handle latch willl lock the charging handle into the receiver.

The next step is to mate the upper and lower receivers together for the first time.

One of the idiosyncrasies of the AR platform is that the upper and lower receivers generally don’t fit together tightly. This isn’t normally considered a problem because it doesn’t affect the bore axis/sight plane relationship, and therefore shouldn’t affect accuracy in any significant way.

The movement created by this loose fit can, however, be distracting…which can affect accuracy…and competition shooters usually try to eliminate it. There are several methods at varying expense levels and effectiveness to reduce or eliminate the slop:

Some manufacturers make matched “national match” upper and lower sets that are specifically made to fit tightly together. Another method is to “glass bed” the action where the gap between the receivers is filled with fiberglass reinforced resin. Another common method is special tightening pivot and takedown pins that are deigned to clamp the receivers together and eliiminate the slack. Or you can go the cheap and easy route like I did and just use an accuwedge.

An accuwedge is a rubbery synthetic insert that fits in the lower receiver below and behind the takedown pin.

As the receiver closes, the accuwedge “wedges” itself into the gap.

The upper and lower receivers are connected at two points. First line up the pivot pin holes at the front of the two receivers…

…and press the pivot pin into place. Sometimes this takes some jiggling to get it all lined up. You should feel the detent “snap” the pivot pin in place as it seats fully into the receiver.

With the pivot pin locked in place and the accuwedge positioned at the rear of the lower reciever, close the two receivers together and press tightly to overcome the tension created by the accuwedge.

And then press the takedown pin in to lock it into place just like you did the pivot pin.

And there you have it.

The only things left are the front sight post and rear sight installations.

Click here for part 10

NM Rifle Build Part 8

In Part 1, we introduced the series and talked about tools.
In Part 2, we installed the magazine catch and trigger guard.
In Part 3, we installed and adjusted the Jewell Match trigger.
In Part 4, we installed the safety selector, pistol grip and bolt catch.
in Part 5, we installed the pivot pin, recoil buffer components and buttstock.
In Part 6, we installed the forward assist and the ejection port cover.
In Part 7, we installed the delta ring and barrel.

This time, we’re going to install the free-float tube and front sight base.

In the last post, I mentioned one of the differences between a rifle with a free-float tube and a standard AR…the special barrel nut.

Another difference is that the sling swivel is mounted on the float tube rather than the bottom of the front sight base (FSB). That way the pressure placed on the sling when in a sitting or prone firing position is pulling on the float tube, not on the barrel.

The problem with this is that the standard A2 FSB has an integral sling swivel mount. The mount on the FSB will interfere with the mount on the free-float tube and, so, it’s gotta go.

This is where the dremel tool and carbon cutting wheel come into play.

Of course, you want to be careful and consider that the more attention to detail you give this, the better the end result will look, but it’s a pretty simple procedure.

Clamp the FSB into a vise with padded jaws (or cushion it with rags or pieces of wood).

Cut the sling swivel mounting ears off as close to the bottom of the FSB as you safety can.

You could use a hacksaw for this and I would imagine it would work fine as long as you’re careful. I like the control that the dremel tool gives, but if you don’t have a dremel tool, you probably don’t need to buy one just for this job.

If you need to take some excess off, carefully grind the remaining stubs down until they are almost flat against the bottom of the FSB.

Then use a fine jewelers file to square it up and remove all traces of the sling swivel mount.

You probably can’t really tell in this picture, but the bottom of this FSB is not completely flat. The areas where the sling swivel mount ears were just removed angle down slightly toward the center, where there is a narrow flat spot. I didn’t file the FSB bottom completely flat, but maintained this angled contour in the areas where the sling swivel mount was removed.

I took another step and used a fine stone to remove the filing marks. You could also use emory cloth sand paper at, say, 400 grit or finer to remove the filing marks.

It doesn’t have to be polished or anything, but you want it smooth enough to look “stock”.

Basically, you want to hack the sling swivel mount off without it looking like something’s been hacked off.

Finally, clean the filings off and hit the bare metal you just made with some cold blue to preserve it and match the finish.

With that prep work done, let’s install the float tube.

The free float tube consists of (in addition to the barrel nut), the tube itself, which has the handguard retainer and sling swivel mount permanently attached, and a lock ring.

On a standard barrel, the handguard retainer is just fitted over the barrel and is held on by the front sight base.

That retainer can be discarded as the handguard retainer in this case is mounted directly to the float tube.

On my Rock River free float tube, the sling swivel was not attached out of the box. The tube came with the sling swivel and rivet, but they weren’t installed.

Installation is simply a matter of putting the sling swivel on the mount on the free float tube, sticking the rivet through the holes, and smashing the rivet down with a big punch and hammer.

Next, you may have left the locking ring on the barrel nut while you were installing the barrel.

If so, that’s fine.

If not, thread it onto the barrel nut exterior threads. and screw it on as far as it will go, but don’t tighten it.

Note the round dimple in the locking ring. That will come into play later.

Then slide the float tube over the barrel with the handguard retainer and sling swivel toward the end of the barrel.

Screw it onto the barrel nut.

This is why we needed to remove the sling swivel mount from the FSB before mounting the float tube.

You need to verify the position of the float tube before tightening it down.

Get the float tube positioned about where you think it should go…then slide the FSB onto the barrel and into place to check its position.

I didn’t think to take a picture when doing this, so I took one later, after the gas tube had been installed already.

The float tube should be as close to the FSB as possible, without touching it. If they touch, the tube will interfere with the barrel and defeat the whole purpose of free-floating the barrel. If you make the gap too great, however, the handguard retainer may end up too close to the delta ring and the handguards may not fit.

Also note the sling swivel below the bottom of the FSB. had we not removed the sling swivel mount from the bottom of the FSB, the sight base would not have fit.

Once you’ve verified the position of the free-float tube, take the FSB back off again.

Unscrew the float tube from the barrel nut 5 or 6 turns. Be sure to count, you want to be able to screw it back in the exact same number of turns.

Then put a bit of blue thread locking compound right where the edge of the float tube will be when screwed back in. Put enough on that it will also be under the locking ring once it is tightened against the float tube.

Screw the float tube back in the same number of turns that you screwed it out.

Then, screw the locking ring out until it contacts the float tube.

Before tightening the locking ring, be sure the float tube is as perfectly straight up and down as possible.

the gap that the gas tube will pass through needs to be centered over the gas port in the top of the barrel.

Remember that round dimple in the locking ring that I pointed out before? This is where it becomes important. There is a section of the AR-15 multi-tool that acts as a spanner wrench. It’s a half-moon looking area with a small peg at the end.

Place the half-moon part around the locking ring so that the peg on the tool locks into the dimple on the ring.

While holding the free float tube to keep it from turning, tighten the locking ring against the tube firmly to lock it into place.

And the float tube is done.

The FSB installation on a match rifle is different from a standard AR-15 in two ways. On a standard AR (and even some match rifles, for that matter) the FSB is held on with tapered pins that pass completely through the FSB and barrel. One of the accepted modifications for a match rifle is to drill and tap the taper pin holes in the FSB and use set screws to hold it on. This allows the FSB to be adjusted for windage. On a match rifle, you want your zeros to be as close to the actual zero settings on your sights as possible so that you have the full range of adjustments as well as having known starting points for all adjustments.

This also means that the barrel is slightly different between a standard FSB and an adjustable one. With a standard FSB, the taper pin holes are drilled through the bottom of the barrel. With an adjustable FSB, there are no holes, but generally “flats” are milled into the bottom of the barrel for the FSB set screws to mate with.

That simplifies the initial installation of the FSB, but complicates finalization because you have to adjust it before securing it permanently. for purposes of just getting it onto the rifle, however, it’s pretty straight forward.

The front sight base installation involves the FSB itself, the gas tube and the gas tube roll pin.

The gas tube is the final difference that results from using a free-float tube.

On a standard gas tube (top), the bend in the tube that accounts for difference in height between the gas block and the tube position in the receiver is just aft of half-way. Because the free float tube encloses the barrel, the bend in a gas tube used with a free-float tube must be much farther forward (to the right in this picture) than with a standard installation. The modified gas tube (bottom) was provided with the free-float tube.

One other note about the gas tube. When I first tried it, the gas tube that came with the free float tube wouldn’t fit into the bolt carrier key at all. I thought I had gotten a defective gas tube at first; however, the gas tube is fairly soft metal. What I did was push them together and spin them both against each other. After working them for awhile, this shaped and shaved the gas tube enough that it eventually fit inside the bolt carrier key smoothly. I don’t have the experience to really know but they may have made the gas tube slightly oversized on purpose with the intent of fitting it to the key for a tight seal.

Now for the FSB installation:

I suppose you could mount the FSB to the barrel first and then install the gas tube, but it made more sense to me to pin the gas tube into the FSB first.

Be sure that the gas tube is inserted into the FSB correctly before installing the pin…the end of the gas tube with the holes goes into the FSB. The small hole that passes completely through the tube is the hole for the roll pin. The larger hole that does not pass completely through is the gas port hole and needs to be pointed toward the bottom of the FSB (toward the barrel when the FSB is mounted).

Be sure to get the roll pin hole in the gas tube aligned perfectly with the holes in the FSB. The gas tube is relatively soft and you will crush it if you try to drive the pin in with the holes misaligned.

The gas tube was a tight fit, so after getting it aligned, we didn’t have to worry about it moving.

A tiny little pin punch could be used to help you get them aligned, or a piece of wire, dental pick or other object small enough to pass through the holes might help. We just aligned it by looking through the hole under magnification which worked fine for us.

The gas tube roll pin is very small so we held it with a pair of needle nose pliers and used the nylon mallet to get it started.

Then finished it off with a pin punch.

Next, make sure the channels in the barrel retaining snap ring, weld spring and delta ring are lined up with the notch in the barrel nut.

Then thread the gas tube through the slot in the float tube,

As you press the FSB into place on the barrel, pass the gas tube through the channel in the barrel nut/delta ring assembly and into the upper receiver.

Double check to make sure there is a gap between the rear of the FSB and the float tube, then install and snug down the set screws that secure the FSB to the barrel.

No reason to use thread locking compound on them or torque them down yet…we’ll need to adjust the FSB to zero with the rear sight first.

And that’s it. Starting to look like a rifle.

(Yes, the delta ring is backward in this picture…as I mentioned in the last post, we didn’t realize this mistake until after we tried to install the handguards. I didn’t think to take another picture after correcting it.)

The barrel installation, including free float tube and FSB, were the most difficult part of the whole assembly.

It really was MUCH easier to perform than it was to describe.

Now that I’ve done it once, I think I could do everything described in the last two posts in about 30 minutes tops.

I would say that as long as you invest in the right tools, have any modicum of mechanical ability, and take your time, this is well within the capabilities of your average gunny.

Next time we’ll install the handguards, install the flash hider, assemble and install the bolt carrier group and mate the upper and lower together.

Click here for part 9

NM Rifle Build Part 7

In Part 1, we introduced the series and talked about tools.
In Part 2, we installed the magazine catch and trigger guard.
In Part 3, we installed and adjusted the Jewell Match trigger.
In Part 4, we installed the safety selector, pistol grip and bolt catch.
in Part 5, we installed the pivot pin, recoil buffer components and buttstock.
In Part 6, we installed the forward assist and the ejection port cover.

This time we’re going to install the delta ring assembly and the barrel.

One of the major differences between a National Match rifle and a standard AR-15 is the addition of a free float tube.

Basically, what this entails is attaching a rigid tube from the front of the barrel nut to just behind the front sight. The hand guards and sling swivels are attached to this tube, rather than to the front sight base. The idea is that, when properly using the sling, there is a lot of tension on the front sling swivel. on a standard AR, this tension can cause the barrel to flex. With the barrel “floating” inside this tube, no pressure, either from the hand guards, or from the sling tension, is placed on the barrel, but is taken up by the float tube, allowing the barrel to resonate naturally with each shot, thereby improving accuracy.

You can free float any AR and improve accuracy, but it is most common on match rifles. With match rifles, also, it is important that the external appearance of the rifle remain stock. Free floating the barrel is an accepted modification, but you have to use standard handguards.

As usual, click all pix to make bigger

The free float tube comes with a special barrel nut that is different than a standard nut.

The standard barrel nut is only threaded on the inside where it mates with the upper receiver and does not extend past the gear-like “head”.

The barrel nut used with a float tube, on the other hand, looks the same up to the “head” but extends past that area and is threaded on the outside. Those extended exterior threads are what the float tube screws onto.

Notice the groove machined into the unthreaded part of the barrel nut on both the standard style, and the free float tube style barrel nut.

The barrel installation involves the special barrel nut, the barrel and the three components of the delta ring assembly: delta ring, weld spring and snap ring.

The barrel installation itself is identical whether using a float tube or not, the only difference in this part of the assembly is which type of barrel nut is used.

First, the barrel nut should be placed on the bench with the exterior threaded part (or the “head” with a standard barrel nut) down.

Place the delta ring over the unthreaded part of the barrel nut. The slope of the delta ring should be sloping in toward the bottom.

We actually installed the delta ring backward initially. I thought it looked funny, but I couldn’t quite pinpoint why. Everything fit fine (although it was harder than it should have been to torque the barrel nut with the delta ring in the way) and we didn’t realize what the problem was until we tried to install the handguards…which wouldn’t fit.

This is what it looks like with the delta ring installed backward.

It shouldn’t look like this. If you can see the weld spring, you did it wrong.

Next, the weld spring goes over the barrel nut and should fit down inside the delta ring.

Then, using the snap ring pliers, install the snap ring into the groove machined toward the edge of the barrel nut.

You’ll have to compress the weld spring a little to get the snap ring on, but it isn’t very hard if you use a properly sized set of snap ring pliers.

You can probably do it without the pliers, but they make it much easier.

With the upper receiver in the action block and the action block securely fastened in the vise, install the barrel onto the lower receiver.

The indexing pin in the barrel extension should seat fully into the notch in the upper receiver threads.

Next, grease the upper receiver and barrel nut threads with a good molybdenum disulfide grease.

Popsicle sticks can really come in handy…and they’re cheap. I bought a bag of 250 for a couple of bucks a few years ago and still have probably half the bag left.

There are as many opinions about what kind of grease to use as there are AR-15’s in the world. As a Honda motorcycle owner, I just happened to have a very good Moly-B (that’s what we used to call molybdenum disulfide based grease in the Navy) that’s used on the drive shaft splines of my bike. That’s what I used.

The only real dire warning I’ve found about the grease selection is to not use grease with graphite in it because graphite can act as an electrolyte and increase the chances of dissimilar metal corrosion due to the barrel nut being steel and the receiver being aluminum.

I have no idea how valid that concern is but it was something I ran across when researching this project.

After applying a little grease with the popsicle stick, I used a rag to even it out and remove excess. You don’t need a lot, just enough to put a light coat on the threads.

The purpose of the grease is to act as an anti-seize compound and to prevent galling of the receiver threads while tightening the steel barrel nut.

Next, slide the barrel nut over the barrel with the external threads toward the end of the barrel and the interior threads toward the receiver.

Thread the barrel nut onto the receiver threads and hand tighten.

The next step is where the AR-15 multi-tool was critical.

There is a square hole in the center of the multi-tool just behind the barrel nut part of the tool. That hole is designed for a 1/2 inch drive torque wrench to fit.

The barrel nut should be tightened to a minimum of 30 pound feet and a maximum of 80 pound feet.

Now…I probably went a little overboard, but knowing that using an extension alters the actual torque from the setting on the wrench, I used the magic formula to make sure the torque setting was accurate:

Torque setting on wrench (Ts) = Actual torque desired (Td) times lever length of the torque wrench (Lw) divided by lever length of torque wrench (Lw) plus length of the extension(Le).

Ts = Td(Lw/(Lw+Le))

Since we’re using pound feet, all measurements have to be in feet.

The lever length of the torque wrench is from the center of the grip to the center of the drive. Mine is 15 inches or 1.25 feet. The length of the extension is from the center of the drive, to the center of the torque wrench attachment point…1.5 inches or .125 feet. With long extensions, you have to account for the angle that the wrench is attached to the extension as well, but for one this short, as long as the angle isn’t too great, it won’t make much difference.

So: Torque desired (Td) = 30 pound feet
Lever length of torque wrench (Lw) = 1.25 feet
Lever length of extension (Le) = .125 feet

T(s) = 30(1.25/(1.25+.125))
T(s) = 30(1.25/1.375)
T(s) = 30(.909)
T(s) = 27.27 pound feet

So, I set the torque wrench to 27 pound feet rather than 30. Not a huge difference, as I suspected, but better safe than sorry right?

After the nut is tightened to the minimum torque, the next step is to see if you have a notch in the barrel nut “head” aligned with the gas tube channel.

You’ll probably have to move the snap ring, the weld spring and the delta ring in relationship to each other to line up all three of the channels with the barrel nut.

A dental pick or “L” shaped allen wrench works well for this.

A good way to check the alignment is to stick the gas tube through the channel and see where it points.

If the tube doesn’t point straight down the barrel centerline, then you’ll need to turn the barrel nut more to get it lined up.

I had an extra gas tube to use because the float tube came with its own gas tube. I just left the tube in place while turning the barrel nut so I’d know as soon as it lined up. I wouldn’t do this with the gas tube I’m going to install because I’d be afraid of it binding and being bent or crushed. If you don’t have a spare gas tube, a piece of thin dowel rod or something like that would work just fine.

The maximum torque is 80 pound feet. Using the formula to adjust for the extension, I came up with a torque setting of 73 pound feet. Set the torque wrench to the maximum and then tighten the nut until the tube is aligned with the barrel or the maximum torque is reached, whichever comes first.

If you reach the max and haven’t gotten the gas tube aligned, stop, loosen and try again. Torque to 30, then try to align the gas tube notch without over torquing. If you still can’t get it, I’d say having it a pound or two under torqued would be better than over torquing it. I’d be very leery of damaging those aluminum threads on the receiver.

If you do have to under torque the barrel nut, I’d check it regularly to be sure it’s not backing out and crushing the gas tube.

After the barrel nut is torqued, the barrel installation is complete.

I did hit the barrel nut with some cold blue after torquing. The multi-tool had scraped the finish off of some of the crowns of the nut and I didn’t want to leave them bare.

No progress picture for you this time…I forgot to take one until after we had the float tube on.

I obviously need more practice at this stuff.

I was originally going to include the float tube installation in this post, but it was getting too long so you’ll just have to be patient.

Next time we’ll install the free float tube and the front sight base.

Click here for part 8

NM Rifle Build Part 6

In Part 1, we introduced the series and talked about tools.
In Part 2, we installed the magazine catch and trigger guard.
In Part 3, we installed and adjusted the Jewell Match trigger.
In Part 4, we installed the safety selector, pistol grip and bolt catch.
in Part 5, we installed the pivot pin, recoil buffer components and buttstock.

This time, we’re going to start on the upper receiver by installing the forward assist assembly and the ejection port cover.

The forward assist assembly is pretty straightforward. It consists of the assembly itself, a large spring and a roll pin.

The forward assist goes into the large, angled hole on the right side of the upper receiver.

On the “post” part of the assist assembly, there is a flat area. that area is where the pin engages and holds the forward assist in. As the assembly is installed, that flat area needs to be in toward the center of the receiver.

The spring slips over the “post” part of the assembly.

Then insert the assembly into the hole, compressing the spring so that the flat on the assembly’s “post” area will line up with the pin hole.

Then drive in the roll pin.

Pretty simple.

The ejection port cover isn’t much more difficult to install.

It consists of the cover and latch assembly, the hinge pin, the spring, and a TEENY TINY retaining ring (It would be VERY easy to lose this so be careful with it. When I first pulled the components out of the shipping bag, the retaining ring was stuck to the ejection port cover itself and I thought it was missing until I spotted it clinging to the preservative oil coating).

We were, for some strange reason, thinking that this installation might damage the finish (silly us…not much chance of that), so we taped the side of the receiver forward and aft of the ejection port. That was completely unnecessary, but better safe than sorry, right?

First, clip the retaining ring into the groove close to the end of the ejection port cover pin. It went on very easily, but, again, be very careful, if you put too much pressure on it and it pops out of your hands, you will probably never see it again.

As I’ve explained in the past, this is one reason for the towel that I always put down on the work bench. If you drop (or launch) small parts while trying to install them, they have less tendency to bounce when they hit the towel, they tend to stop right where they hit and generally are easier to find.

Then put the spring in place on the ejection port cover itself and position it on the receiver.

Make sure the latch on the cover will be in toward the receiver when the cover is closed.

The short arm of the spring goes against the receiver and the long arm goes into the crease in the ejection port cover.

The easiest way I found to do this was to put the long arm in place on the cover door and stick the short arm in the receiver through the ejection port, then drag the cover down into position between the mounting ears, catching the short arm of the spring on the edge of the receiver as it goes. I had to put my finger across the spring to keep it from bending and popping out of position.

While holding the cover and spring in place, from the front of the receiver and with the retaining ring end of the ejection port cover pin toward the front of the receiver, slide the pin in, through the cover and the center of the spring.

It sounds more complicated than it is. It really was very easy to do.

The retaining ring keeps the pin from sliding to the rear and out. After it’s installed, the delta ring keeps the pin from sliding forward and out.

The spring tension was plenty to keep the pin in place until the barrel and delta ring were installed.

And that’s where we’re at.

Next time, we install the delta ring and the barrel.

Click here for part 7