Bolt repair/replacement on WH M1 Thompson

[JonnyDingDongs 158]

I'm a welder with access to a TIG, so I'm hoping this could be a DIY fix, but it's off to a bad start.. I've got an Auto Ordnance M1 Thompson (Semi-auto) made in West Hurley, so apparently I'm screwed on factory parts and service. Lesson learned: I will always research my firearms before purchasing from here on out.

First issue: Fired brass not only has the primer indented, but even the rear of the cartridge has the oval indentation from the firing pin. I've always assumed it to be a 'querk' of Thompsons, but have no basis for comparison. Is this normal, or was this my worst impulse buy ever?

Second (major) issue: The firing pin had sheared the retracting pin almost completely off a couple years back and I attributed this to the gun having the most God-awful heavy springs in the world. To this day, I still can't completely cycle the action by hand without feeling like my finger is about to be ripped off. So my thinking was, "if this thing's going to keep breaking pins until it's broken in, I might as well put in the cheapest pins I can find!" Yeah, normal thought processes and I don't get along very well.. So in my infinite wisdom, I picked up some cheap roll pins, ground one to fit, and drifted it in. A few weeks ago, my buddy and I got together for some target practice and put about fifty rounds through it. Got home, got it apart, and discovered that the bottom of the bolt, just below the holes for the retracting pin, had been shattered. The hardened pin hadn't bent like the stock one, it had torn its way through the bolt. My thinking is to do as I've been trained at work: Put a copper plate behind it, fill the entire area with weld, grind, refinish, and redrill the appropriate size holes at the correct location. I need to know what grade of steel the bolt is composed of so I may buy the correct filler. I tried to contact Auto Ordnance, only to discover that they'd been bought out by Kahr in '99 and their tech guy was less than helpful. Couldn't even answer one question. Awesome. Talked to my local gunsmith and his best guess is 4140, but I'd like to be certain before I spring for a brand new bolt which may or may not fit (once you move a factory, parts are likely to change in my experience.)

Finally, I'll need to know why the firing pin was striking the retracting pin with such force. I'm planning to sell this gun to finance my first AR, but I don't want to sell someone a possibly defective firearm.

Anyone with experience and/or technical knowledge of Thompsons, please help! Thanks in advance and thank you again for those who have helped me already!

[kevin.rose0@gmail.com 62]

I'd post the question in the NFA section too. There are a few people who post there who seem to be familiar with them.

[Shandlanos 1,470]

I have no idea where to find replacement semi-auto bolts. Just to be clear, this is a closed-bolt gun, not a pre-82 open-bolt semi-auto?

[termite 463]

Try www.tommygunner.com

[JonnyDingDongs 158]

I have no idea where to find replacement semi-auto bolts. Just to be clear, this is a closed-bolt gun, not a pre-82 open-bolt semi-auto?

 

Yessir! I'm heading to the local welder's supply shop to pick up some 4140 filler and hopefully get this thing fixed tonight. I can order a new bolt from 'Auto Ordnance,' but since the company was bought out and the factory was moved, who knows if it'll meet the same specs.

[JonnyDingDongs 158]

Too many impurities in the welding process, and I had to make multiple passes. Warped the bolt! Guess that leaves me one choice... Thanks anyway, everybody!