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How often are USGI Thompson kits turned into semi-auto SBR's? Are semi-receivers available? How hard are they to put together? Thanks for your time!
 

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Seen a forum where people rewelded thompson receivers to semi auto specs, but involves a ton of work that seems too much for what it is.

Another route to go is get a doug Richardson semiauto receiver. His are made to all same specs and dementions as the original ones, and think uses the kahr semi auto bolt and trigger parts in a usgi trigger housing(to be legal must work in closed bolt config).

I myself plan to sbr my auto ordnance thompson m1, and modify a usgi m1 trigger housing and stock set to it eventually.
 

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the price an original kit will set you back now + the work involved VS buying a new semi rifle or pistol + $200 . You'll still be ahead going with the new gun.
 

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Seen a forum where people rewelded thompson receivers to semi auto specs, but involves a ton of work that seems too much for what it is.

Another route to go is get a doug Richardson semiauto receiver. His are made to all same specs and dementions as the original ones, and think uses the kahr semi auto bolt and trigger parts in a usgi trigger housing(to be legal must work in closed bolt config).

I myself plan to sbr my auto ordnance thompson m1, and modify a usgi m1 trigger housing and stock set to it eventually.
Modifying the USGI trigger housing would be for aesthetics only correct? I have also filed a form1 to SBR my Kahr - had not considered redoing a triggger housing for it tho....
 

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Looks better with both safety and selector switches in place, and if you have a 1928 type, can modify selector switch to act as the bolt hold open, eliminating the 3rd hand thing to change drums. I'm wanting to rounds the edges of my m1 receiver to look like they did originally, but it's beyond my expertise.
 

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I had planned on looking into adding/modifying the S/A lower with a non-functional selector switch, but it kind of fell by the wayside temporarily. I would think stamping the markings would pose some difficulty - although I'm sure Ryan could probably do it for me....
 

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I have a couple of pieces of an M1 receiver that have been laying around a while that I might eventually work on. Anyone know anything about heat treating an M1 receiver after welding? Is it necessary and what Rockwell where? That's something I've never seen discussed.
 

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medalguy,

In general receivers are hardened in the 43 RC range +- , barrels are 36 RC and bolts are in the 45 RC range . This is industry accepted standards ,as far as a M-1 Thompson being a blow back action these numbers may not apply ,but i suspect it still applies .
 

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So - I am curious - how do builders of semi autos on a GI receiver deal with the required dimension changes inside ? Does a regular FA bolt fit too ? Fire control being closed bolt would seem to be a problem using the original parts ? I have several receiver parts sets and parts - if there is a cheap easy way to use them for something that would be great......
 

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So - I am curious - how do builders of semi autos on a GI receiver deal with the required dimension changes inside ? Does a regular FA bolt fit too ? Fire control being closed bolt would seem to be a problem using the original parts ? I have several receiver parts sets and parts - if there is a cheap easy way to use them for something that would be great......
Only usable parts in the fire control group would be trigger, mag catch, and I think the safety. Would need to widen groove where original sear ect went, to fit new semiauto parts.
 

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How often are USGI Thompson kits turned into semi-auto SBR's? Are semi-receivers available? How hard are they to put together? Thanks for your time!


ive got a semi conversion out in 1928a1 & m1a1 & m1's....

its been done several hundreds of times on the various forums since i made it public. ive done over 200+ conversions for people as well.

the work itself is NOT hard. its just time consuming. it uses all US compliant parts (ar stuff inside) & is super reliable.

the good, bad & true of it all?

good:

its exact weight, feel, look & passes EVERY test the ATF has. INCLUDING hammer follow thru & runaway tests. still uses all original parts & off the shelf parts you can get everyday to maintain this thing for ever. runs ANY ammo. steel, brass... it just doesnt care.


bad:
i came up with this when the kits were everywhere & they were cheap. which meant you could do your own Tommy for LESS than the $1200 semi garbage guns that you can buy every day of the week. .. so "we" ate up the kit supply in a hurry & now they are pretty pricey.


true:
well if you just want to buy a semi tommy? its cheaper to get the $1200 version now days & not have to do the work, BUT they dont feel the same as a real tommy & arent a real tommy. they arent even close. & they look ridiculous with that 16" barrel + compensator giving them the anteater look.

heres a quick couple of pix & any of the guys here can point you to my build threads on how to do these ( i no longer do conversion jobs... just no time for it.)

below is a 28 with a modified 16" barrel instead of the SBR which is exactly the same other than the stamp..

and then the m1a1 in pistol set up to avoid the stamp... again function is exactly the same.

DSC01180.JPG M1 Tommy.jpg
 

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I went the Kahr Thompson SBR route myself. I had the military style markings laser engraved on the upper and some inspectors initials to simulate a wartime rebuild. I also had the fire control selector added as well as the FA pivot plate. 10 inch barrel was installed. Tears ago took a scotchbrite disk and rounded off all the sharp corners and edges and had the whole thing parkerized. I know parkerization is not the correct finish but like I said it represents a rebuild. Finally I added USGI wood. Very happy with how it came out despite the costs. The rifle only cost me $700 in 1998 but I think the work done to it cost about as much.



 

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Very nice. I hope mine ends up at least as good as yours. I kinda like the parkerized finish myself. I'm torn on weaqring the compensator or just the front sight option. I lean towards the 1928 style with the comp in place [like Saunders in Combat] :tongue:
 

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Discussion Starter #15
ive got a semi conversion out in 1928a1 & m1a1 & m1's....

its been done several hundreds of times on the various forums since i made it public. ive done over 200+ conversions for people as well.

the work itself is NOT hard. its just time consuming. it uses all US compliant parts (ar stuff inside) & is super reliable.

the good, bad & true of it all?

good:

its exact weight, feel, look & passes EVERY test the ATF has. INCLUDING hammer follow thru & runaway tests. still uses all original parts & off the shelf parts you can get everyday to maintain this thing for ever. runs ANY ammo. steel, brass... it just doesnt care.


bad:
i came up with this when the kits were everywhere & they were cheap. which meant you could do your own Tommy for LESS than the $1200 semi garbage guns that you can buy every day of the week. .. so "we" ate up the kit supply in a hurry & now they are pretty pricey.


true:
well if you just want to buy a semi tommy? its cheaper to get the $1200 version now days & not have to do the work, BUT they dont feel the same as a real tommy & arent a real tommy. they arent even close. & they look ridiculous with that 16" barrel + compensator giving them the anteater look.

heres a quick couple of pix & any of the guys here can point you to my build threads on how to do these ( i no longer do conversion jobs... just no time for it.)

below is a 28 with a modified 16" barrel instead of the SBR which is exactly the same other than the stamp..

and then the m1a1 in pistol set up to avoid the stamp... again function is exactly the same.

View attachment 14481 View attachment 14482
PM inbound soon. This is exactly the type of project I was looking at.
 

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GB,

thought i had that build posted here too... but heres links to my original build threads on these with my usual crappy pix & a whole lot of info at WG or GUNCO..

in that same area there are also semi tommy designs by JoeH, Jim44 & several other very good gunbuilders.

as with any of my designs.. they are free for anyone to use/copy as long as its NOT FOR PROFIT. (people who want to do it for profit.. gotta pay or come up with their own)

the 28a1:
http://www.weaponsguild.com/forum/index.php?topic=833.0

the m1 & m1a1:
http://www.weaponsguild.com/forum/index.php?topic=7124.0

if you have any questions im always available.

s
 

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I have a 1928 kit and a Philadelphia Ord "block of steel" receiver that I was going to make into a semi but I think I'm going to make it into a dummy instead. Anyone interested in milling a narrow channel into the block of steel to lighten the receiver and drilling and tapping it for the rear sight?
 

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Can anyone tell me if the receiver threads of 10 TPI Square are the same for original Thompsons AND the newer Kahr/Auto Ord remakes? I know the dimensions of the receiver are different, but did they change the specs of the barrel too as far as threading? I have a Green Mountain barrel and the threads seem a tad tight [thick] compared to the barrel that came on the TM1.
 

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Dang! If that don't beat all. And I just finished sleeving a threaded bushing into a comp to put on the end of that short GM barrel. Figured I could use it. Hmmmmm.....oh well........:(
 
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