NM AR Rifle Build Part 3

In Part 1, we introduced the series and talked about tools.
In Part 2, we installed the magazine catch and trigger guard.

This time, we’re going to install the Jewell match grade, 2 stage adjustable trigger and go over the adjustment procedure.

The Jewell is pretty plainly not the absolute best trigger out there; and I have read some reviews complaining about them being too hard to adjust or not having the longevity that they should. As far as the first complaint, I’d say they either installed it wrong or were not adjusting it properly. Only time will tell whether the second complaint is accurate or not. I will say that, now that I’ve gotten mine installed, I’m very happy with it so far.

One of the biggest complaints about the Jewell trigger is that the installation instructions suck. That one I can wholeheartedly agree with. Hopefully, this post will come in handy for those intrepid souls who scour the internets for information that will make their lives easier.

As usual, click all pix to make bigger

The Jewell trigger assembly is very different from the standard trigger and hammer assembly.

Fortunately, the hammer spring is already installed in on the hammer out of the box and the trigger and disconnector assembly are already assembled.

This simplifies things considerably.

BTW: The nammer and trigger pins do not come with the trigger. You have to buy them separately. They do make both small pin and large pin versions of the trigger so you can get what you need for your lower.

The first step is to figure out how the trigger return spring fits on the trigger.

It goes on the left side of the trigger.

The spring has a bent leg and a straight leg.

The bent leg goes toward the trigger and the tip should be pointing up. There is a small “peg” on the left side of the trigger that this bent leg should catch on when properly installed.

Place the trigger into the lower receiver with the spring in this position.

It may not stay perfectly aligned because it’s a pretty loose fit. That’s OK, as long as the loop is positioned so the pin will go through it, you’re OK.

Next, while holding the trigger and spring to keep them aligned with the trigger pin holes, insert the trigger pin. FROM THE RIGHT SIDE (I’m yelling because this is important) and with the offset groove to the right.

Don’t put the pin in all the way yet, just enough to keep the trigger from falling out.

Now, slide the first stage adjustment plate in between the trigger return spring and the side of the receiver. If you pushed the pin in too far in the previous step, you may have to pull it back out a little to get the plate to go in.

The plate should be installed with the “teeth” pointing inward toward the trigger and the flat edge down toward the bottom of the receiver.

Line the plate up with the trigger pin hole, be sure that loop in the spring is still aligned with the trigger pin, and finish pushing the trigger pin the rest of the way in.

Next, the straight arm of the trigger return spring has to be brought up to engage the teeth in the first state adjustment plate. This is where the wire tool that came with the trigger came in handy.

One end of the wire is hooked. Use that hook to snag the straight arm of the trigger return spring and pull it up until it engages the adjustment plate. Which tooth it engages isn’t important at this point, as long as the spring is engaged in the adjustment plate teeth.

As you put tension on the spring, if it’s installed correctly, the bent arm of the spring should engage the peg on the left side of the trigger assembly.

Mine hooked right in. I’m sure if it doesn’t, you could just jiggle or move it around a bit until it pops into place.

AFTER the straight arm of the trigger return spring is engaged in the adjustment plate teeth, it’s time to install the hammer. If you forget and put the hammer in first, you’ll have to take it back out because the trigger return spring won’t fit past it once it’s installed.

The hammer’s pretty straightforward.

There is a cylindrical “roller” type bearing on the front part of the hammer spring. That roller goes against the front of the receiver.

As the hammer is pushed down into position, pry it back against the spring tension and lever the bottom in toward the front of the receiver.

Once you get the pin hole in the hammer aligned with the holes in the receiver, you can insert the hammer pin, again with the offset groove to the right.

It might make it easier to use a pin punch to line everything up and then push the pin punch out with the hammer pin.

Next, the hammer and trigger pin retainer goes in. On a standard trigger assembly, the hammer and hammer spring engage the grooves in the hammer and trigger pins to lock them in place. The Jewell trigger, because of the difference in design, doesn’t have that locking mechanism built in.

That is the purpose of the pin retainer.

From the right side of the receiver, gently push the trigger pin until it clears the side of the receiver. You just need it to clear the side of the receiver, don’t push it completely out.

Slip the loop end of the pin retainer between the right side of the trigger and the wall of the receiver.

the straight arm of the pin retainer should be pointing forward and down toward the hammer pin.

Once the loop is in position, seat the trigger pin fully back into place.

For the next step, the other tool included with the trigger comes in handy.

Use the wedge end of the tool to gently pry the hammer spring away from the right side of the receiver.

You’re trying to create a gap large enough for the pin retainer to slip through.

Once you have a gap between the hammer spring and receiver wall, use the notch in the trigger tool to push in and down on free end of the pin retainer.

Slip the arm of the pin retainer between the hammer spring and receiver wall, and so that the retainer is to the rear of the hammer pin.

Press it down until the half-loop in the pin retainer snaps around the hammer pin.

Once the pin retainer is in place, it should be under tension between the two pins.. The tension should force the two wire loops into the grooves in the hammer and trigger pins and lock them into place.

I pushed the pins back and forth slightly a few times while pressing down on the visible part of the the pin retainer to ensure that it locked into the grooves.

That’s it for installation. That wasn’t so bad now was it? Now for adjustment.

***IMPORTANT NOTE*** it is not good for the lower receiver to dry fire without the upper installed. Dry firing without the upper causes the hammer to impact the aluminum front of the trigger well in the receiver. Since aluminum is a relatively soft metal, this can cause damage to the receiver.

All is not lost, however. What I do is stick a popsicle stick between the front of the hammer and the rear wall of the receiver. When the hammer falls, it hits the popsicle stick versus the aluminum receiver and prevents damage to the receiver wall. This destroys the popsicle stick within about three or four dry fires, but popsicle sticks are significantly less expensive than lower receivers and are not regulated by the ATF (yet). [/NOTE]

There are four adjustment points for this trigger. The first is the first stage trigger pull (aka takeup) that is adjusted by the tension of the trigger return spring. This can be changed by moving the straight arm of the trigger return spring into different teeth of the first stage adjustment plate.

Both of the trigger tools were useful for this adjustment. When the trigger return spring is toward the front (least tension) end of the adjustment plate, the hooked end on the wire tool seemed to work best for pulling the arm back into the higher tension ranges of the adjustment plate.

But after the half-way point, it seemed easier to use the notched end of the other trigger tool to push the spring into the higher range of the adjustment plate’s positions.

I was very impressed with the range of adjustment options that this setup gave for the first stage trigger pull tension.

The other three adjustments are made by turning allen head set screws on the trigger assembly itself.

The first of these adjustments to make is the sear engagement adjustment.

This adjusts how far the trigger moves during the second stage of the trigger pull…after the trigger makes contact with the sear, how far it moves before the sear releases the hammer.

This movement is also called “creep”. The more creep there is, the less “crisp” the trigger is. With too much creep, the trigger can feel mushy or gritty as it releases.

Too little creep is a problem as well though. If there isn’t enough sear engagement, the hammer may fail to lock back after firing and “follow” the bolt down as it closes. At best, this means that the hammer won’t be cocked between shots and you’ll have to manually operate the bolt to cock the hammer. At worst, this condition can cause uncontrolled full auto fire. Not only is uncontrolled full auto bad for your scores in competition, but it can result in an out of battery cartridge detonation which is a very convenient method of turning your upper receiver into a hand grenade.

One other point about adjusting the sear engagement. This screw cannot be accessed with the hammer cocked. That means you should go slowly and make very small adjustments. If you get overzealous, you could adjust it to the point that the hammer won’t release at all. This is bad because, as I said before, you can’t reach the screw with the hammer cocked. If the hammer is cocked and won’t release, and you can’t reach the adjustment screw…there is only one way to adjust it: take the hammer and trigger pins out, remove the whole trigger assembly to release the hammer, adjust some of the sear engagement out, and then reassemble the whole thing.

I’m sure you can imagine how I figured that one out.

At any rate: The way I adjusted the sear engagement is, I basically adjusted it down until I had a hair trigger. Then I put maybe an eighth of a turn of engagement back in to be sure the engagement was sufficient to be safe. After firing my first 20 rounds through it tonight, that method seems to have worked well: no failures of any kind. So far so good.

The next adjustment is the second stage pull.

This is what determines how much pressure is required from the end of the first stage “takeup” until the trigger releases.

This is adjsuted with the larger allen screw on the rear of the trigger assembly.

You can adjust this down to the point that there is no appreciable second stage…the pull is smooth all the way until the hammer releases…or up so that significant force is required to release the hammer.

According to the instructions, Jewell recommends adjusting the first stage pull to 3 1/2 pounds, and then the second stage to 1 pound, for a DCM legal 4 1/2 pounds of pull.

While experimenting and dry firing, that didn’t feel “right” to me. The takeup felt too tight and the second stage release didn’t feel sufficient to give me a distinct release point. I decided to lower the first stage and increase the second stage a little. By my rinky-dink pull gauge, I read a first stage of 2 1/2 pounds and a release at 4 1/2 pounds for a second stage of 2 pounds.

I have to say that, after shooting it tonight, I think I was wrong. I’m going to adjust it closer to Jewell’s recommendation. What felt good when dry firing, didn’t feel so good when actually shooting. The first stage felt OK, but the release was too tight. It was crisp and clean, but just too heavy. I’m going to reduce the second stage, but to keep it within the DCM legal 4 1/2 pound range, I’m going to have to increase the first stage by an equal amount. That’s going to put me right around where Jewell recommended to begin with: 3 1/2 pound first stage, 1 pound second stage.

I guess they actually knew what they were talking about.

The final adjustment is overtravel.

This controls how far the trigger continues to the rear after the hammer releases.

It is adjusted with the small allen screw on the front right of the trigger assembly.

Overtravel (arguably) isn’t quite as critical to a good trigger pull as the sear engagement and pull weights, but it does make a difference in the overall feel of the trigger. When the trigger stops moving to the rear just as the hammer releases, it just feels more precise and actually makes the second stage pull weight feel less than it actually is. In other words, you can probably get away with a long overtravel distance, but the entire trigger experience is improved by reducing it.

The bst way to adjust the overtravel is to turn the screw in until the hammer simply won’t release at all. You can do that with this adjustment because you can still get to the screw with the hammer cocked. Once you’ve got it down to where the hammer won’t release, back the screw out a about a quarter turn and pull the trigger. If the hammer still doesn’t release, back the screw out another quarter turn and try it again. Repeat just until the hammer releases.

That’s the minimum overtravel you can have and still release the hammer.

That’s it. The trigger is installed and adjusted, so here’s where we’re at.

Next time well install the Safety Selector and Pistol Grip, and the Bolt Catch.

Click here for part 4


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