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Repair Question on Semi Auto Thompson


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#1 Grease Gunner

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Posted 01 October 2018 - 11:31 AM

Hello All:

 

A number of years ago, someone tried to disasemble a semi auto pistol and had no clue

how to do it and tried to force the parts out of the lower without separating the lower from

the upper and got things stuck.

 

It was sent to a repair facility and it got repaired but with an access hole drilled

into the trigger guard. Does that make any sense?

I am not the one who sent it in, just the current owner

 

 

9KKiaQ.jpg

 


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#2 halftrack

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Posted 01 October 2018 - 01:38 PM

Yes, it makes sense. I once had a firing pin break in half resulting in not being able to separate the frame from receiver. Out of desperation I tried to start removing parts one by one which made the situation worse. The thought was if I could remove the trigger I then would be able to fish all the internals through that hole therefore making more room for the broken firing pin to fall and finally separate the frame from the receiver. It didnt work because the trigger guard prevented the trigger from dropping completely out. The hole in your trigger guard I assume allows for the trigger to drop out through the bottom. Not a bad idea considering I had to cut my frame off and had to order a new one.

Edited by halftrack, 01 October 2018 - 01:39 PM.

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#3 Grease Gunner

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Posted 01 October 2018 - 06:50 PM

Thanks!!


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#4 deerslayer

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Posted 11 October 2018 - 06:37 PM

I have fixed many broken firing pin semis. The firing pin breaks in the middle and the back half dives into the trigger Assembly area. You have to know what you are doing but you can usually do laproscopic surgery and get it apart. Taking out the pivot plate is a very bad idea...
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#5 Mainecoon

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Posted 19 October 2018 - 07:31 AM

Is there a stronger aftermarket firing pin that can be installed in these in attempt to avoid the hassle and mess of repairing the broken stock firing pin?
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#6 Merry Ploughboy

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Posted 19 October 2018 - 08:26 AM

Is there a stronger aftermarket firing pin that can be installed in these in attempt to avoid the hassle and mess of repairing the broken stock firing pin?

 

I'm guessing probably not.  The firing pin is flat but has small, medium, and large areas which means that it is difficult to uniformly heat treat to get the desired strength and durability.  In the AR-15 world, .22 and pistol caliber firing pins have a similar breakage issue due to approximately the same cause, except the firing pin is round with multiple diameters.  Unlike the semi auto Thompson, the AR-15 firing pin is easy to replace; and most .22 and pistol caliber AR-15 owners carry a spare.

 

And a question about the repair: Wouldn't it have been better to cut the leg off the trigger so that the trigger body could drop down and getting a replacement trigger instead of drilling a big hole in the trigger frame?

 

MHO, YMMV, etc.


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#7 StooperZero

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Posted 19 October 2018 - 09:14 AM

having the BHO pawl spring break is a treat too. 

 

 

but it can be taken apart when things are bouncing around inside. 


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#8 deerslayer

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Posted 19 October 2018 - 03:03 PM

There are no aftermarket better firing pins.. and the old style West Hurley pins aren't even made by anyone... So the solution becomes but a new bolt.
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#9 T Hound

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Posted 17 December 2018 - 11:08 PM

Hmmm...interesting discussion.  Haven't been unfortunate in this way yet, but food for thought.  Perhaps there might be
a way to modify bolts, with pins for instance, that prevent the broken halves of the firing pin from falling into the trigger parts
cavity and causing such a jam up.  Food for thought!

Edited by T Hound, 17 December 2018 - 11:09 PM.

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#10 Paladin601

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Posted 17 December 2018 - 11:37 PM

any pictures of broken firing pins?


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#11 T Hound

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Posted 19 December 2018 - 11:00 PM

any pictures of broken firing pins?

They would certainly be useful and instructive if they show a pattern of breakage.


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#12 Paladin601

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Posted 20 December 2018 - 11:45 PM

any pictures of broken firing pins?

They would certainly be useful and instructive if they show a pattern of breakage.

Exactly, what I was thinking


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#13 T Hound

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Posted 21 December 2018 - 12:06 AM

I have fixed many broken firing pin semis. The firing pin breaks in the middle and the back half dives into the trigger Assembly area. You have to know what you are doing but you can usually do laproscopic surgery and get it apart. Taking out the pivot plate is a very bad idea...

From what you say here, it sounds like I should be checking my firing pin for cracks on a regular basis.


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