Tommy gun firing pin breakage

"DOLLY" · September 3, 2010, 07:47 PM

ALL
i have a buddy with an auto-ordnance "tommy-gun" whose firing pin litterally broke in half and now the bolt will only actuate half way open and will not allow him to dis-assemble the weapon. The other half of the firing pin fell out of the weapon when he pulled back on the bolt.

so, question 1) has anybody ever heard of this?
2) is there a technique for allowing dis-assembly of the bolt and associated components?

thanks for any and all replies, there will definitly be a follow up on this one.

**44 AMP** · September 4, 2010, 10:53 AM

Is the bolt stuck part way back? If you can get it closed, you ought to be able to get the upper off, and disassemble from there.

My extractor broke, about the 3rd mag I shot. Bolt was jammed half way open. After a while, and while trying to get the upper off, it cleared enough to go forward, and things came apart ok after that, uncluding what was left of the broken extractor.

Replaced extractor, and the gun has run fine ever since.

And no, I don't hold the broken extractor against the maker. I got the gun used (looking new, but used), and a broken extractor (or firing pin) is something that can happen to any gun, at any time.

If its still under warranty, send it back. If you can get it apart and fix it, fine. IF not, take it to a gunsmith.

Dfariswheel · September 4, 2010, 06:53 PM

Due to the really odd-ball Auto Ordnance Semi-auto firing pin breakage, while not common, is not unusual.

The firing pin is a weird dogleg design, made from a stamping. The stamping leaves a rough, ragged edge surface that causes stress risers and can lead to breakage.

The best way to do it is to turn the gun upside down and gently "wiggle" the bolt back and forth to try to get the broken section to drop back into the bolt.
Once you get the pin back in place, you can disassemble the receiver from the trigger group.

If you can't get it apart, send it back to Auto Ordnance for repair.
If you can get it apart, buy a new firing pin and use stones to smooth up the stamped edges. Don't remove much metal, just get some of the ragged edges slightly smoothed to help prevent stress breakage.

k Squared · December 31, 2022, 10:10 AM

The Auto Ordnance parts page mentions that a new firing pin must be "fitted by a qualified gunsmith".
Does anyone have the procedures for this fitting?
I put a new firing in, and it is dragging across the sear block to the point where the bolt will not go all the way to the rear.
I assume I need to file the bottom of the firing pin just enough to allow it to pass over the top of the sear block, while leaving enough length to fully engage the back of the sear.
If anyone can confirm this, I would be eternally grateful.

**44 AMP** · December 31, 2022, 03:09 PM

Sorry I can't confirm the cure. What I can say (to a point) is that the Auto Ord guns made after Kahr took over are slightly different than the guns made earlier.

According to one Tommy gun guy I spoke with (years ago, now..) Kahr had changed the gun, from a threaded barrel to a press fit barrel, and that bugged him, because, as he put it, "the first thing that wears out is the barrel!" and he could no longer change them himself. The press fit gun had to go back to Auto Ord (Kahr) to get a new barrel installed.

Its not impossible that other changes were also done, and that MIGHT be why the website says "must be installed by gunsmith". Or it could just be CYA for Kahr, I don't know.

The Tommy gun I had was Auto Ord made, but came with a Kahr manual. I think it was one that had been built before Kahr took over and was packaged and shipped by Kahr shortly after they took over.

The really "wonky" internal design was the result of trying different things to make the ATF (of the day) happy that it couldn't be "readily converted" to full auto, so they would approve manufacture.

Hope you get yours up and running, but I'm afraid I can't offer anything beyond good wishes. Good Luck!

**4V50 Gary** · December 31, 2022, 07:03 PM

Not too long, not too short. Some guns have a firing pin protrusion guage for go/no go examination by the armourer.

You can proably reverse engineer it and make one on a lathe of tool steel and then harden it.

Shadow9mm · December 31, 2022, 07:11 PM

I seem to remember the firing pin breaking in the Thompson, in general, was not an uncommon thing. Something with the design of it making it prone to breaking. I would be sending it back to auto ordinance to get fixed.

**44 AMP** · December 31, 2022, 08:45 PM

Firing pin breakage problems in the Thompson is only common to the semi auto "1927" guns. The full auto guns using a much different pin, and the GI model M1A1 use a fixed firing pin.

k Squared · January 2, 2023, 09:00 AM

44 AMP,
Thanks for the info on the pressed barrel. You just saved me a bunch of money on a project that wouldn’t have worked.

Nodak1858 · January 2, 2023, 12:53 PM

I bought a 1927 AO Tommy gun 2 years ago, has screwed in barrel.

k Squared · January 2, 2023, 01:24 PM

At least I know to ask how the receiver is configured before I buy it.

September 3, 2010, 07:47 PM	#1
"DOLLY" Junior Member Join Date: September 3, 2010 Posts: 1	Tommy gun firing pin breakage ALL i have a buddy with an auto-ordnance "tommy-gun" whose firing pin litterally broke in half and now the bolt will only actuate half way open and will not allow him to dis-assemble the weapon. The other half of the firing pin fell out of the weapon when he pulled back on the bolt. so, question 1) has anybody ever heard of this? 2) is there a technique for allowing dis-assembly of the bolt and associated components? thanks for any and all replies, there will definitly be a follow up on this one.

September 4, 2010, 10:53 AM	#2
44 AMP Staff Join Date: March 11, 2006 Location: Upper US Posts: 27,184	Is the bolt stuck part way back? If you can get it closed, you ought to be able to get the upper off, and disassemble from there. My extractor broke, about the 3rd mag I shot. Bolt was jammed half way open. After a while, and while trying to get the upper off, it cleared enough to go forward, and things came apart ok after that, uncluding what was left of the broken extractor. Replaced extractor, and the gun has run fine ever since. And no, I don't hold the broken extractor against the maker. I got the gun used (looking new, but used), and a broken extractor (or firing pin) is something that can happen to any gun, at any time. If its still under warranty, send it back. If you can get it apart and fix it, fine. IF not, take it to a gunsmith. __________________ All else being equal (and it almost never is) bigger bullets tend to work better.

December 31, 2022, 10:10 AM	#4
k Squared Senior Member Join Date: June 10, 2007 Location: Albuquerque, NM Posts: 238	Firing Pin Fitting - Semi-auto Thompson The Auto Ordnance parts page mentions that a new firing pin must be "fitted by a qualified gunsmith". Does anyone have the procedures for this fitting? I put a new firing in, and it is dragging across the sear block to the point where the bolt will not go all the way to the rear. I assume I need to file the bottom of the firing pin just enough to allow it to pass over the top of the sear block, while leaving enough length to fully engage the back of the sear. If anyone can confirm this, I would be eternally grateful. __________________ K Squared

December 31, 2022, 03:09 PM	#5
44 AMP Staff Join Date: March 11, 2006 Location: Upper US Posts: 27,184	Sorry I can't confirm the cure. What I can say (to a point) is that the Auto Ord guns made after Kahr took over are slightly different than the guns made earlier. According to one Tommy gun guy I spoke with (years ago, now..) Kahr had changed the gun, from a threaded barrel to a press fit barrel, and that bugged him, because, as he put it, "the first thing that wears out is the barrel!" and he could no longer change them himself. The press fit gun had to go back to Auto Ord (Kahr) to get a new barrel installed. Its not impossible that other changes were also done, and that MIGHT be why the website says "must be installed by gunsmith". Or it could just be CYA for Kahr, I don't know. The Tommy gun I had was Auto Ord made, but came with a Kahr manual. I think it was one that had been built before Kahr took over and was packaged and shipped by Kahr shortly after they took over. The really "wonky" internal design was the result of trying different things to make the ATF (of the day) happy that it couldn't be "readily converted" to full auto, so they would approve manufacture. Hope you get yours up and running, but I'm afraid I can't offer anything beyond good wishes. Good Luck! __________________ All else being equal (and it almost never is) bigger bullets tend to work better.

December 31, 2022, 07:03 PM	#6
4V50 Gary Staff Join Date: November 2, 1998 Location: Colorado Posts: 21,680	Not too long, not too short. Some guns have a firing pin protrusion guage for go/no go examination by the armourer. You can proably reverse engineer it and make one on a lathe of tool steel and then harden it. __________________ Vigilantibus et non dormientibus jura subveniunt. *Molon Labe!*

September 4, 2010, 06:53 PM	#3
Dfariswheel Senior Member Join Date: May 4, 2001 Posts: 7,426	Due to the really odd-ball Auto Ordnance Semi-auto firing pin breakage, while not common, is not unusual. The firing pin is a weird dogleg design, made from a stamping. The stamping leaves a rough, ragged edge surface that causes stress risers and can lead to breakage. The best way to do it is to turn the gun upside down and gently "wiggle" the bolt back and forth to try to get the broken section to drop back into the bolt. Once you get the pin back in place, you can disassemble the receiver from the trigger group. If you can't get it apart, send it back to Auto Ordnance for repair. If you can get it apart, buy a new firing pin and use stones to smooth up the stamped edges. Don't remove much metal, just get some of the ragged edges slightly smoothed to help prevent stress breakage.

December 31, 2022, 07:11 PM	#7
Shadow9mm Senior Member Join Date: March 21, 2012 Location: Indianapolis, IN Posts: 3,620	I seem to remember the firing pin breaking in the Thompson, in general, was not an uncommon thing. Something with the design of it making it prone to breaking. I would be sending it back to auto ordinance to get fixed. __________________ I don't believe in "range fodder" that is why I reload.

December 31, 2022, 08:45 PM	#8
44 AMP Staff Join Date: March 11, 2006 Location: Upper US Posts: 27,184	Firing pin breakage problems in the Thompson is only common to the semi auto "1927" guns. The full auto guns using a much different pin, and the GI model M1A1 use a fixed firing pin. __________________ All else being equal (and it almost never is) bigger bullets tend to work better.

January 2, 2023, 09:00 AM	#9
k Squared Senior Member Join Date: June 10, 2007 Location: Albuquerque, NM Posts: 238	44 AMP, Thanks for the info on the pressed barrel. You just saved me a bunch of money on a project that wouldn’t have worked. __________________ K Squared

January 2, 2023, 12:53 PM	#10
Nodak1858 Senior Member Join Date: September 7, 2009 Location: N. Dakota Posts: 425	I bought a 1927 AO Tommy gun 2 years ago, has screwed in barrel. __________________ We've all heard that a million monkeys banging on a million typewriters will eventually reproduce the entire works of Shakespeare. Now, thanks to the Internet, we know this is not true.

January 2, 2023, 01:24 PM	#11
k Squared Senior Member Join Date: June 10, 2007 Location: Albuquerque, NM Posts: 238	Thanks…Again At least I know to ask how the receiver is configured before I buy it. __________________ K Squared

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