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Discussion Starter #1
I've finally obtained all the parts I need to get started on the Thompson! All I've done so far is clean the demilled receiver up a little & started laying out the design.

1928a1 005.jpg mags 002.jpg

Now for the particulars........

I have a 1928A1 Thompson SMG kit from Omega Systems. It's one of the Russian lend lease weapons from 1940-1942, in great condition.
Going with the 14.125" new manufactured "finned" barrel from Green Mountain. When the compensator is affixed, it will be the legal 16+" to make it a carbine.
Doing away with the Bish Lock and using an AR fire control package in semi.
Welding an original de-milled receiver from IMA, with the ATF compliant blocker bar & obstructions so a full auto receiver cannot be fitted to the lower.

The biggest challenge I see with this build is going to be the extensive mods to the original bolt. Along with all the BATF regulations......I've got to machine the bolt so it will work with the AR hammer. Then doing the mods so it will be transformed from an open bolt to a closed bolt design. I also plan on modifying the selector switch into the safety & the safety into a bolt hold open lever.
I'm really excited about this one. Hopefully my welding skills with the new mig set-up will be up to par. One more thing for everyone thinking about building.........I build all my projects at home in my back room or carport, with very limited equipment. I'm a painter by trade, so there goes all the opinions that only machinists & welders can build these things.
Well, off to lay this thing out. I do want to make sure I have a sound design before I start cutting & welding things.

I'll keep you posted, Matt
 

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Good luck on the build. Can't wait to be updated

I almost like the barrel not being blued.
 

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Discussion Starter #3
Getting closer..........picked up some copper to use as a backing plate for the welds. I'll hopefully pick up a loaner jig for the magwell this weekend, & if nothing goes wrong, I should be able to weld up the receiver over Thanksgiving break. I'll keep ya posted & add pics when it starts to look different.

Matt
 

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Discussion Starter #7
Sweet! I thought long & hard, but couldn't justify the extra $200 for a tax stamp right now............with a 9mm PPS43, Sten MKIII, & a couple of AK's waiting to be built, plus the daily urge to order an Uzi kit. I have become a total kit junky lately :p
 

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Discussion Starter #8
Finally started welding. That nosepeice is a little tricky keeping true & square, but I'll get it. Here's what I've got so far. Still have alot of welding & cleaning up to do, and then get the internal mods started. I welded the blocking bar in before joining any sections. Late for breakfast, so I'll give more details later.



Build 012.jpg Build 016.jpg Build 017.jpg Build 019.jpg Build 023.jpg


Matt
 

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Finally started welding. That nosepeice is a little tricky keeping true & square, but I'll get it. Here's what I've got so far. Still have alot of welding & cleaning up to do, and then get the internal mods started. I welded the blocking bar in before joining any sections. Late for breakfast, so I'll give more details later.



View attachment 485376 View attachment 485377 View attachment 485378 View attachment 485379 View attachment 485375


Matt
Please explain the placement and purpose of the "blocking bar". Do you have any drawings of the new AR FCG?
 

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Discussion Starter #11
QUOTE=03man;1950186]Please explain the placement and purpose of the "blocking bar". Do you have any drawings of the new AR FCG?[/QUOTE]

Sorry for taking so long to get back.........busy weekend. The purpose of the blocking bar is to prevent an un-modfied FA bolt from being install & able to chamber a round in the semi gun. I won't be using the Bish Lock, so I welded a piece of keystock into the milled channel inside of front-top of the receiver. I will mill a channel on the top corner of the bolt to clear the bar.

I don't have any drawings of the modifications to be done to the FCG. I plan on milling a slot in the bottom of the bolt to allow for the AR hammer to swing clearly to the firing pin. After I get the slot milled, I will be able to take measurements on where the firing pin mounting holes have to be drilled in the lower. I will also have to do a little milling to the lower, so the AR trigger package will fit inside the cavities, along with a slot for the FP springs so they won't jump out. I'm pretty sure I'll have to shave a little off of the bottom of the trigger to fit inside the trigger guard. After I get it up & running, I plan on cutting both the original & AR firing pins in half, then grafting/welding them together so I will have the original portion on the exterior, & the AR working parts hidden in the interior. The selector switch should be able to be modified to a new safety & the original safety latch converted to a bolt open lever.....I plan on using drums & the range master will like it if the bolt can be locked open.

I will update pics & what measurements I come up with when I get to those stages. There are several other guys building these over on weaponsguild.com. I took a look at several of them & am picking stages/ideas that I like from different builds & incorporating them to my single project.

Matt
 

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Thanks Paintman,
that is pretty clear. Can't wait for the rest of the story.

I was under the impression that re-connecting the receiver pieces was a No=no, un less it was somewhat shorter than the original? Is it? Or am I mistaken, again?

Thanks.
 

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Discussion Starter #13
Thanks Paintman,
that is pretty clear. Can't wait for the rest of the story.

I was under the impression that re-connecting the receiver pieces was a No=no, un less it was somewhat shorter than the original? Is it? Or am I mistaken, again?

Thanks.
Different builds will dictate details on what to do to the FA receiver before welding it back together. According to the BATF, an original full auto bolt cannot be intsalled to chamber a round (hence the blocking bar) & in this case, the semi upper cannot be easily attached to a full auto upper. For that, I welded up a section in the lower rail & ground the corrosponding rail from the upper so the 2 will connect. My lower will know, not fit on a FA upper & vise versa. You beat me to the punch. When I get the kit back out to work on it, I'll take pics & show you what I'm talking about. I also did the first mod on my bolt before welding the receiver, so I would not have a FA bolt & receiver in the house at the same time......I fill welded the sear slot, I think that's what it's called - so the bolt would not catch in the "open bolt" position.

Try to be patient with me....I plan on going over each phase/component one at a time as not to make it too confusing.

Matt
 

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Discussion Starter #14
Got a little carried away with the welding (my patience was broken that day) and I warped my receiver!....I had to cut the nosepeice off & do it again. This time with an aluminum angle & lots of clamps (more than in the pic). Also decided to thread the barrel on so I could double check on alignment and to see if things were moving while I was working. I really took my time & basically "tack welded" the entire thing, including all the filler. Worked great. I now have a straight upper. All I need to do is some finish welding (cosmetic) along with plenty of grinding.......then I'll be able to work on some more mods.


. Build 026.jpg Build 025.jpg
 

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Discussion Starter #15
Here's what I have so far, still have a little shaping and hand-filing to do, so now it's time to start the semi mods.


Build 027.jpg . Build 028.jpg
 

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Discussion Starter #16
Started cutting/fitting the lower. I already did the compliance mods (filled channel on lower, cut groove in upper to match) so you can not mount a FA upper to lower & vise versa. Got the AR trigger & hammer to fit & operate. Started on cutting/fitting -through the receiver- components. Next I'll have to modify the Full Auto/Semi switch to act as my new safety. If anybody needs details, let me know. I've got to get ready for tonight's festivities.........& yes it involves belt-feds & blanks.
Those are the "in-progress" builds on the wall. Assembled for test fitting. My buddy -jreed- & I are building 1928's together. Mine is on top.


Build 036.jpg Build 037.jpg Build 039.jpg Build 040.jpg

Happy New Year! Matt
 

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I can't wait to see how this turns out. I'm a huge fan of the aesthetics of the 1928A1 (and Thompsons in general). Any plans to ever make it into an SBR so it can use the original barrel?
 

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Discussion Starter #18
I would love to SBR it one day, but with a milled AK, Sten MKIII, RPD, & another 1919 in the works..........I just couldn't justify the $200 stamp right now. I do have a spare compensator & am always on the lookout for a 10" barrel. Hopefully one day when the smoke clears, I could write a check, fill out the paperwork & change the barrel out, but first, lets see if I can get this thing hopping. When it's done the only change in the exterior appearance, should be the extra pin holes for the hammer........one on each side, and of course the longer barrel. I plan on making my own pins out of drill stock with rounded points to mimmick the original pins & such.
 

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Discussion Starter #19
Cut to the chase..................

Well, I skipped posting a lot of steps.........but I finally finished it!!
I may jump back & add some detail on the ending stages of the build if anyone's interested. If anyone has any questions, ask away & I will answer what I can.

Worked flawlessly out on the first trip to the range. Ran brass cased Aguila & steel Tula without a hitch or misfire. 20rnd, 30 rnd stick & 50 rnd drum ran great.



Here's how it scored
2.12.12 003.jpg

Actually, it's finished mechanically. I still plan on making it pretty. Right now it has a temporary coat of cold blue & I havn't touched the stock yet.

Matt
 

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Very cool. I've recently been bitten by the Thompson bug and I'd like to build an SBR from a new semi-auto. What tools are needed to properly swap out the barrel?
 
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