M1 Carbine Part 7: Trigger Housing reassembly

In M1 Carbine Part 1, we took a look at the external condition of the new old CMP M1 Carbine.

In M1 Carbine Part 2, we disassembled the M1 Carbine into its major groups.

In M1 Carbine Part 3, we disassembled the Trigger Housing Assembly into its individual components.

In M1 Carbine Part 4, we disassmbled the bolt without using the M1 Carbine Bolt Tool (don’t try this at home kiddies).

In M1 Carbine Part 5, we removed the components from the stock and receiver that were necessary to remove for inspection and discussed those items not removed.

In M1 Carbine Part 6, we examined the component markings and determined whether the parts are correct for the period and manufacturer.

In this edition, we’re going to reassemble the Trigger Housing. It really wasn’t too difficult, but there were a couple of areas that required some patience.

The first step is to place the safety into the housing.

It goes in from the right side.

Then the safety/magazine plunger assembly goes in. That’s the spring with plungers on both ends.

It goes in from the front. It fits into a hole in the housing between the front of the trigger guard and the rear of the magazine well.

Next is the magazine catch spring and plunger. That’s the spring with a plunger on only one end.

It goes in from the right side in the hole forward of the safety.

Next is the magazine catch. It slides in from the right side. In order to get it to go in, you have to compress the safety/magazine catch plunger assembly. There is a hole in the bottom of the housing for this purpose, but I found it easier to compress the plunger assembly from the front and pull the pin punch out of the way once the catch was in far enough to retain the plunger assembly.

It really takes two hands but one was occupied with the camera so I simulated with one hand just to illustrate.

After the catch is pushed on far enough, the magazine catch plunger will snap into the groove and hold the catch in place. At that point, rotate the safety a couple of times to ensure that it moves freely but locks into the “safe” and “fire” positions correctly.

The next thing to put in is the trigger.

That’s pretty self explanatory.

Start the trigger pin into the holes but only put it in far enough to catch the edge of the trigger to keep it from sliding around too much while the sear and sear spring are going in.

For some reason, I failed to take a picture of the sear spring going in. There is a well in the top front of the trigger and a matching well in the rear bottom of the sear. Drop the sear spring into the well in the trigger.

Then the sear goes in over that. The longer end of the sear goes forward, the shorter end (may have a hole in it) goes to the rear.

The next part is also a two handed operation and was the most difficult part of the assembly.

You must press the sear to the rear to compress the sear spring, line it up with the mounting holes and the press the trigger pin through the hole in the sear, the hole in the other side of the trigger and then the hole in the side of the housing. What made it complicated was that, with pressure on the sear, it kept going too low to line the holes up; to get it to raise up, pressure would have to be relaxed which would allow the sear spring to push it forward, which would take it out of alignment again. Press to the rear and the sear would also go down at the same time. I ended up having to put slight pressure on the pin and then move the sear around gently until I lucked into getting them lined up enough for the pin to start into the sear…but then the whole thing went cock-eyed and out of alignment so I had to press on the part of the trigger sticking through the trigger guard to get it lined back up again, which made the sear shift enough for the pin to slide back out…ARGHHHH!

Needless to say, this took some patience. I can’t tell you any super whammy-dyne trick to do it. Just keep playing with it and eventually, when the stars (and the parts) align and the rifle Gods smile on you, it will just slip in like it was no big deal.

In fact, when the pin finally pushed in, it went so easily and took me so much by surprise I just stood there with a confused look on my face momentarily thinking “what happened?” It took me a second to realize it had actually gone together.

Next is the trigger spring. This can go in from the front or through the hole in the rear. I put it in from the rear.

After you force it into the right general area, you’ll have to pry it into the correct position. I used a jeweler’s screwdriver.

It should lock into a lip on the top of the trigger.

So far so good. Now the hammer goes in.

And the hammer pin. The hammer pin goes in from the right so that the head is on the right side of the housing after assembly.

Next, assemble the hammer spring and hammer spring guide.

The spring and guide go into a hole in the rear part of the housing.

Stick a pin punch through the hole in the front of the hammer spring guide for leverage.

Pull back on the guide to compress the spring. Make sure the guide goes into the hole in the housing. The spring will try to push to the side which will cause the guide to catch and not go into the hole. You may have to guide it a little with one hand.

Once you get it back far enough to clear the hammer, rotate the pin punch so it is horizontal.

Then pop the guide into the well in the rear of the hammer.

Remove the pin punch.


VIOLA! One fully assembled M1 Carbine Trigger Housing Group.


Sorry…Too much coffee.

Next time we’re going to reassemble the bolt without the luxury of the M1 Carbine Bolt Tool.

Now THAT one required a lot of coffee! Not fun.

See you soon.


7 thoughts on “M1 Carbine Part 7: Trigger Housing reassembly

  1. Awesome guide on the M-1 Carbine! Been meaning to do a full teardown but could't find a manul. I have a 1944 Underwood and was afriad to attempt the trigger group without some help. Thanks for the great how-to and the clean happy M-1 that was the result.
    J.P. in SC

  2. Pingback: M1 Carbine Part 11: Using the M1 Carbine bolt tool (assembly) | Captain of a Crew of One

  3. Pingback: M1 Carbine Part 9: Major group reassembly | Captain of a Crew of One

  4. Pingback: M1 Carbine Part 8: Bolt reassembly (ugh!) | Captain of a Crew of One

  5. Thanks for the detailed instructions!

    I still had trouble with big old fingers getting the trigger spring into place. Slid a piece of para cord through the spring loops and out through the hole and pulled it right into place from the top.

Leave a Reply

Your email address will not be published.

This site uses Akismet to reduce spam. Learn how your comment data is processed.