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#1 hvac

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Posted 20 November 2005 - 12:59 PM

here is the questions I have I want to buy a parts kit to convert to semi-auto I know at one time during the 20s or 30's there was a semi-auto only version was this done through the trigger group or the receiver (if it was the receiver is there any machinist prints) if it was done throught the trigger group could you take out the selector switch and weld up the hole then modify the bolt assembly for semi-auto operation which model would be better for doing this the 1928A1 or the M1A1? is there someone out there doing this modification already I know it would be cheaper to buy a semi-auto but I just don't think it would be the same as I said I am very new to this any information would be appreciated I would just buy a real Submachine Gun but it is out of my budget does anyone have any thoughts on a semi-auto conversion thanks.
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#2 Zamm

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Posted 20 November 2005 - 03:58 PM

hvac,
Your refering to the 1927 Thompson Semi-automatic Carbine. These are quite rare, being actual 1921 models that had some of the firing mechanism parts replaced. The Stamped "Model of 1921" was ground off and re-stamped with "Model of 1927". Also "Thompson Submachinegun" was ground off and replaced with "Thompson Semi-Automatic Carbine".
Probably less then 150 were converted to this model.
Problem is, all you have to do is remove the semi parts and drop in the parts from a 21 or 28 and you have yourself a full auto again. And that is what the ATF would not care for, not to mention that open bolt stuff.
So, I'm not sure how or what the laws are for registering a semi that fires from an open bolt compounded with you manufacturing a NFA wepon... Others here on the board are much more versed on this subject.
But if I were you, I would just get an existing semi and spice it up with some parts kits and other nifty things one can do, or bit the bullet and get a full auto if you live in an NFA state.
Be a shame to weld up anything on a full auto...not very many left sad.gif
Here's those pesky parts of the actual 27 Semi Carbine.
Best, Zamm
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#3 giantpanda4

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Posted 20 November 2005 - 04:08 PM

I hope this is not the case.... but it sounds like you are trying to make a F/A into a semi - and why? Is it because you have a unregistered F/A reciever? I hope not.

I may be incorrect here - some one step in anytime - but the original semi autos are still required to be registered just as a full auto would - because they can be converted so easily.

Zamm make the best suggestion I could come up with anyway - and then you get two toys to play with!

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#4 Sgt

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Posted 20 November 2005 - 05:08 PM

When I first came into this hobby, I thought I could reweld the demilled receiver back together and make it into a legal semi. I wanted the most authentic thing on the block, but still keep on the right side of the law. My reasons were noble, but dead wrong. Not saying this is what you have in mind, but thought I pursue this line of thinking, just as claification.

First off, the Feds take a dim view of putting those pieces back together. Even if you could, the problem would be in the dimensions. Since the dimensions would be identical as the full autos, the ATF feels you could easily mill it out and put in a full auto bolt. The semi design on the market today, deals with this by making the reciever a tenth of an inch less tall. With this in mind, the orginal parts kit would help you little, unless you began with the semi receiver dimensions, semi bolt and parts, and all the semi trigger parts. This is why the only practical route is to begin your project using the Kahr currently on the market. You can see, it's not just a question of cost, but rather that you would have to build almost everything from scratch anyhow. Search the board and you will see scads of ideas for cosmetically making these look authentic.

To summarize what Zamm said, those old 27s from the gangster era are now considered in the same classifications as a machinegun.

My apologizes if you knew all the above already and I misunderstood what you really had in mind. the Best biggrin.gif
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#5 hvac

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Posted 20 November 2005 - 06:38 PM

QUOTE (LIONHART @ Nov 20 2005, 05:47 PM)
Welcome to the group. This topic has been brought up many times before, and usually the same answers given. I'm not aware of any other "Approved" ATF Designs for a Semi-Auto Thompson other than the one that Numrich had gotten approval for back in '75, and in which the current Company, Karh still utilizes. There is another source for Semi-Finished Thompson Submachine Gun Receivers through Phil Ordnance, and they claim these can be manufactured into a Semi-Auto, though to my knowledge, plans don't exist to do so. The question is, can one take one of these Receivers, or a Doug Richardson TSMG Receiver, and build a Semi-Auto Rifle for themselves? We do know that Federal Law allows an Individual to construct their own Semi. But what are the current guidelines for a Home built Gun, other than it meet's certain criteria? IE-16" Barrel, Semi-Auto only. I think this is where a lot of confusion comes from. IF your intent is building a firearm for the purposes of manufacturing them for Sale, you will need to submit a Prototype to the ATF for examination. However, an Individual constructing a Firearm for their own us, from what I understand, doesn't need to submit any Prototypes to ATF, and so long as it meets the above Guidelines (There may be more..If there is, and if someone out there has them, by all means post it here) one should be OK. Does this mean someone can acquire an 80% TSMG Receiver, construct it to utilize all FA Parts, and simply installing a Trigger Housing modified for Semi-Auto use? NO. As the Receiver is actually the Machine Gun, not the Frame. If however, there were some sort of Modifications made to the Receiver, whereas, it wouldn't accept an Original Bolt, unless Modified, perhaps then, it would be OK for a Home built Gun, and not for Resale/Manufacturing Purposes. However, would one still be able to construct an Open Bolt Semi? I don't have an answer to that, as I haven't been able to find any answers on the ATF's Website. Again, perhaps someone out here can provide additional information. I do believe that another Design for a Semi-Auto Thompson could be worked out, versus what's currently available. As far as a Home built Gun, I would write the ATF with what the Plans called for, and see what they have to say about it.

LIONHART is more on the same page as my thinking but let me add some comments
1. I don't have a Full Auto I am not wanting to weld the old receiver back my thinking is on a 80% receiver and milling it to a semi-auto.
2. If the trigger group doesn't have the selector in it or can't be reinstalled wouldn't this make it a full time semi-auto sense it takes the selector switch to make full-auto
3. some say it is the open bolt but Powder Springs made semi-auto Mac 10's
4. some say it is because how easy it would be to put the full-auto parts back in the receiver well all the AK 47's being built all it would take is 5 minutes with a drill to covert it back to full-auto\
5. yes this would be for my personal use not for sale
I appreciate all the comments and would like to hear everbodys thoughts on this

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#6 Zamm

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Posted 20 November 2005 - 10:19 PM

QUOTE
3. some say it is the open bolt but Powder Springs made semi-auto Mac 10's

Hvac,
Indeed, there were a few open bolt semi's that were allowed by the ATF (like the Thompson look-alike Fox Carbine), but that is not the case anymore.

Open Bolt=NFA , semi or not...

Best, Zamm

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#7 Sgt

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Posted 20 November 2005 - 11:56 PM

hvac--
Just a quick comment about the 80% receivers, I remember a thread that discussed using these to make a semi gun. In terms of legality, many felt that this could be problematic, since these receivers have identical dimensions as the full autos. The only approved design required the use of one with smaller dimensions. I believe Doug Richardson made some 80% receivers with the approved dimensions for semi.
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#8 TSMGguy

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Posted 20 November 2005 - 11:59 PM

Hvac,

You're probably better off just buying one of the new generaton semis from Kahr. They really look pretty good, and you could go the SBR route if you wanted the correct barrel length. As the other posts suggest, you basically cannot use a receiver that will accept an original bolt, nor can you use an open bolt design.

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#9 Zamm

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Posted 21 November 2005 - 09:00 PM

Lionhart,
You know what, I've just been under that impression myself...
Interesting, I thought it was signed into some ATF law during the eighties, like you sad.gif
I guess they just make it pretty darn hard to approve a semi with that mechanisim, not worth the trouble.
Best, Z
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#10 hvac

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Posted 22 November 2005 - 06:34 PM

I have been doing some more research an open bolt is a bolt with a fix firing pin a closed bolt is a floating firing pin well the 1928A1 is a floating firing pin that makes it a closed bolt right? therefore if you do away with the selector switch like you do when you build a AK 47 would it not be a legal semi-auto?
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