1927A1 Thompson Not cocking back all the way.

[NaughtyMonkey]

I got the Thompson from my Uncle who has since passed away. I can't ask him what is going on. I tried the firearm with .45 Snap caps. The mags lock in place but when I cock the handle back and slide forward it doesn't grab a round. When I look closer with a flash light, the bolt doesn't seem to go back far enough to grab a round. So I decided to dissemble watching multiple youtube videos. I noticed two things that didn't seem right. First off one recoil spring is missing. Also the hammer / firing pin block (different videos called it different things) seems way to long and it's hollow inside. Doesn't look right to me. Please see the attached photo.

Also it was transferred before he passed. It does have a Bullet button and I don't own any high cap magazines. I just haven't function tested it until today.

[FeuerFrei]

I have the M1 version and mine has 2 recoil springs and that pin should be solid and is actually the hammer.
Looks like somebody did some tweaking to the rifle. Maybe it was an attempt to lighten the spring tension because they were having feeding/cycling problems.
I would buy new springs and hammer and reassess it with live ammo at the range. Snap caps won't tell you much with these rifles in my experience.
These are fun little rifles when you get them running right. The trigger belongs on a cordless drill but once you get used to it, it is lots of fun.
Brass cased 230gr. ball ammo only for testing purposes.
Good luck.

[NaughtyMonkey]

I have the M1 version and mine has 2 recoil springs and that pin should be solid and is actually the hammer.
Looks like somebody did some tweaking to the rifle. Maybe it was an attempt to lighten the spring tension because they were having feeding/cycling problems.
I would buy new springs and hammer and reassess it with live ammo at the range. Snap caps won't tell you much with these rifles in my experience.
These are fun little rifles when you get them running right. The trigger belongs on a cordless drill but once you get used to it, it is lots of fun.
Brass cased 230gr. ball ammo only for testing purposes.
Good luck.

Thank you, if you don't mind can you measure your hammer. I'll measure mine and see if that is the problem. I really think its too long and that is what is causing it to not go all the way back.

[FeuerFrei]

Hammer is 1 3/16" long. Solid pin.

Pictured hammer seems too long to me also.

[NaughtyMonkey]

It was the hammer. Here is a comparison picture.

[FeuerFrei]

Great!
If everything else checks out O.K. it"s time to test fire.
*You did get new springs?


Sent using a long string & 2 cans.

[NaughtyMonkey]

Yes I did. the one that was in it was also shorter. I also got an extra extractor because I read that those break easy. Figured a spare wouldn't hurt.

[FeuerFrei]

Sounds reasonable.

My bolt hold open has been getting wonky (last few times shooting anyway) and I'm gonna replace the spring if it's not gummed up with crap. It has been a long while since I blew it out with carb cleaner.

Hope you get yours running.


Sent using a long string & 2 cans.

[NaughtyMonkey]

I havn't had a chance to go to the range yet. But I have 200 rounds of .45 Aluminium. The Aluminium should work right?

[FeuerFrei]

Don't do it while testing for function.
You need to confirm proper function with ammo it was designed to run. Introducing an unknown into the mix early on could throw things off.
I have had mixed results with steel cased (Wolf/Tula) and aluminium cased (Blazer) ammo in my Thompson.
Save aluminium cased for something else for now.

Test it only with 230gr. brass cased.
Example = Walley World --- Remington UMC works great in my rifle.

[NaughtyMonkey]

My aluminum cases came from Walmart. (I work there, hehe) It's federal. Runs through 1911 great. It's super cheap. But I'll pick up some brass ammo and then try the aluminum. If it works. I'll be able to shoot her for very cheap. haha.

[FeuerFrei]

I run steel/aluminium cased in my 1911's etc. and it always works great for me too.
This Tommy gun is a different animal.
Just verify function with 1 or 2 boxes of brass 230 stuff while testing.
Once that's done you can try the other. YMMV. Mine did.

[NaughtyMonkey]

How did it perform in your Thompson, like what happened where your not really recommending it? Just curious.

[FeuerFrei]

How did it perform in your Thompson, like what happened where your not really recommending it? Just curious.

Once in a while a round will not feed properly and sometimes empties would hang up.
I attributed this to the rough cases. Switching to brass cleared that up so...