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Repro Lebman mini Colt Thompson question.


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#1 Global Collector

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Posted 24 July 2020 - 05:03 PM

Hi all, new to posting on the forum, I've been here a few times in the past to do some reading, love the historical content and discussions there of.

 

Anyway,

 

   I'm in the process of building my own semi-auto only, NFA Form 1ed, H Lebman colt mini replica (though not on a period colt as this going to be a shooter).

 

  My questions are related to how the TSMG grip is mounted to the 1911 frame.

I've seen several of the replicas members here have built, but i've never seen or read how the originals were mounted.

 

  On this forum, ive read variations of attachment ranging from riveting, to silver soldering, to tig welding the grip mount on.

 

I like the idea of solid welding as I want the front grip to be SOLID when handled a lot even by only the front grip. 

 

   I was thinking of cutting a nice tight fitting notch in the rear of the shortened grip mount that fits on both sides of the front of trigger guard, up where it sits next to the rounded under side of the frame  and welding the top part of the mount to the rounded lower half just above the trigger guard. these welds would be covered by a modified TSMG Grip.

 

What do you folks think of this method? Am I crazy for wanting to weld it?  Is there much risk of stripping out the threading of the grip bolt and the grip mount and not being able to repair?

Is this a safe place to weld on the 1911 frame or do I risk the frame warping from the heat?

I plan to modify a new manufactured Thompson grip mount which are fairly $$ for what they are, and want to make deliberate plans before I start cutting and welding expensive parts.

Thanks for reading my post!

 


Edited by Global Collector, 26 July 2020 - 07:42 PM.

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#2 jl7422

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Posted 24 July 2020 - 10:46 PM

My suggestion would be to make your own grip hanger out of bar stock and add a threaded screw boss. Then it'll fit your frame perfectly. 

 

Welding (and any warping) will be a reflection of the skills of the welder, and what type of weld is used. If I were welding the hanger on I'd go TIG, in the form of spot welds through holes in the hanger.   

 

Just my .02 cents -- Sandy and I dinked around with these a bit. 


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#3 Global Collector

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Posted 24 July 2020 - 11:28 PM

  jl7422 Thanks for the reply,  So your saying to not weld the mount to the trigger guard but just to the bottom of the frame in front of the trigger guard? I was concerned this area was too thin, but im not a welding or gun smiting / 1911 expert by any means.   Im not going to weld this personally as im not skilled enough for nice looking welds, only functional equipment repairs... I need to find a sympathetic smith, willing to take on the project in the midwest.   I have seen and read the many posts and enthusiasm Sandy had for the subject. It is sad his time of contributing is gone, I hope some, if not most of his knowledge and research material is in good hands.

 

 I have included a drawing of my original idea for modifying the TSMG  grip mount.


Edited by Global Collector, 26 July 2020 - 07:44 PM.

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#4 jl7422

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Posted 25 July 2020 - 11:45 AM

I just don't know that notching around the trigger guard gains you much structural support. And by the time you shorten and reprofile a Thompson hanger, for me it's just quicker to make one from scratch. I think Dan Block built a full auto version recently. He might have insight on hanger design. 

 

The ones I'm familiar with have the hanger secured to the frame in front of the trigger guard--either with solid steel rivets or spot welds through the hanger. 


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#5 Global Collector

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Posted 25 July 2020 - 02:02 PM

OK, Thanks for the input!  I'm kind of leaning toward the DIY mount now. It makes economic sense anyway.

 

Like I  said im just stumbling through ideas at this point, dont really have a extensive background in gunsmithing.

 

IF Dan Block or anyone else could provide their info or pictures of the mounting attachment also that would be helpful as well.


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#6 StrangeRanger

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Posted 25 July 2020 - 03:07 PM

The original grip mounts (and the re-pops) are hardened steel, the Waffenmeister re-pops are hardened to Rc 57-58.  Not quite the Hinges of Hell but getting there.  When you weld hardened steel  two things happen, neither of them good: it gets soft spots in the heat-affected zone and it warps.  Just make a grip hanger out of 1/2" hot-rolled steel bar stock.  You'll be saving time, money and headaches.

 

Also the forearm screw in a TSMG is a #14 (.242" dia.)  Do yourself another favor and for your application change to a 1/4"-28UNF which is a MUCH more common size.  You may or may not have to open up the hole in the wooden grip by a few thousandths


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#7 Black River Militaria CII

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Posted 25 July 2020 - 04:42 PM

My suggestion is to fabricate a mechanical joint rather than weld one to the frame for many reasons. The radius of the outside forward extension of the 1911 grip frame is easy to duplicate to make and fit a grip bracket for a forward grip. The bracket can be screwed to the bottom of the frame extension through the bottom with two or three screws properly countersunk for the screw heads. The rear spring guide keeps the spring off the bottom of the extension so the screws have a bit of room to be proud of the inside radius. You can make the grip mounting tongue on the bracket as long or short as you want to accommodate the length of the top of the pistol grip. The depth of the bracket will assure a solid connection for the screws and if the tongue is as thick as or thicker than that of the Thompson brackets, the forward grip can be affixed in the same manner as the Thompson. FWIW

Edited by Black River Militaria CII, 25 July 2020 - 04:59 PM.

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#8 Global Collector

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Posted 26 July 2020 - 09:49 AM

OK so to clarify, the screws used for attachment are going down from inside of the frame into the tapped mount with the head inside the frame?

 

or  going up through the mount and threaded into the frame with the heads countersunk into the bottom side of the mount?


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#9 deerslayer

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Posted 26 July 2020 - 07:09 PM

The last two I did involved drilling two holes through the pistol frame and then welding into the short piece of hanger through the holes. Looked good (invisible) when done and plenty strong.

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#10 deerslayer

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Posted 26 July 2020 - 07:11 PM

With grip

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#11 Global Collector

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Posted 27 July 2020 - 01:53 PM

Thanks  deerslayer, I just feel like weld might be stronger for handling, with the long front grip providing lots of leverage, over a long term / time of use,

As a NFA Item, I would like the piece to last generations if possible. Appreciate the pictures too.


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#12 Black River Militaria CII

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Posted 27 July 2020 - 08:20 PM

Any choice of attachment to the frame extension should go from the top down to the bracket. Plug welding is a fine option but must be done correctly for good penetration through the hole into the bracket. I'm old school and prefer the craftsmanship of mechanical solutions. I do a lot of welding for repair of vintage MGs and it has it's place, of course, and in this application my preference would be mechanical.

In my opinion you are significantly over estimating the stress on the bracket from the pistol. How many twisted, warped, bent or broken grip mounts have users of this site seen on forward gripped Thompsons? Hardly any at all...... Given the hard usage of military Thompsons equipped with the forward grips, one would expect to see that little piece of metal holding the grip thoroughly abused due to the  weight of the gun and the torque possible from rough handling by the grip.
Anyway make it look really good!  FWIW


Edited by Black River Militaria CII, 27 July 2020 - 09:29 PM.

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#13 HANS

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Posted 28 July 2020 - 02:47 PM

With grip


Gorgeous. I see you even installed the fire selector. Kudos. What kind of magazine do you use with this? What rate of fire are you getting with this?

 

Cheers

 

HANS


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#14 StrangeRanger

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Posted 28 July 2020 - 03:24 PM

http://www.machinegu...showtopic=24087


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#15 deerslayer

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Posted 28 July 2020 - 07:01 PM

The video on the link page post was the prototype... And I made that one full auto only. The picture above is the select fire version. They ran the same speed... Fast... It's a handful to hang onto..
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#16 Global Collector

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Posted 28 July 2020 - 08:44 PM

 Well this discussion has certainly given me some guidance. Thanks all for your input so far! Many forums are not so open right off to new accounts. This has been great!

 

Am I correct in saying the tubing made compensators are just tacked onto the standard bushing?

I bought one of the widely available 3 slot comps made by Innovative Industries ( or something close to that) They are nice, made of steel, but too short. I contacted the company about making a longer one. They replied and said they may consider a small batch in the future. I don't feel like waiting that long... when it may never come.


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#17 deerslayer

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Posted 28 July 2020 - 10:04 PM

The comp in my picture started as a big threaded for silencer type that I spun down on the lathe. FTF industries made for a Mac silencer. It doesnt have a noticable effect on barrel rise but it looks good. By the way a semi pistol with the front grip would transfer to you as a $5 AOW... If you do the form 1 AOW yourself then it's $200. Weird atf rules.
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#18 HANS

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Posted 29 July 2020 - 12:26 AM

 It doesnt have a noticable effect on barrel rise but it looks good.


 

This is what the FBI concluded in the 1930s as well. The home-made 7-slot comps, work presumably done by Hyman Lebman, didn't work. Special Agent Baughman went to Lyman (who of course made the Cutts) and they examined the things, finding that since they weren't cut at an angle and had too much room inside they didn't actually compensate. They did look nifty back then as well ...

 

Cheers

 

HANS


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#19 Global Collector

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Posted 29 July 2020 - 10:12 PM

deerslayer, Thanks for the tip, I just took a look at them and I may have to pick one up!

 

HANS, just curious if you know the source for that info of SA Baughman taking it to Lyman? Id like to read it if can find it. I just read the FBI file of  Agent Gus Jones searching Lebman's shop and Lebman's statements. Neat stuff to read first hand!


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#20 HANS

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Posted 31 July 2020 - 07:35 AM

HANS, just curious if you know the source for that info of SA Baughman taking it to Lyman? Id like to read it if can find it. I just read the FBI file of  Agent Gus Jones searching Lebman's shop and Lebman's statements. Neat stuff to read first hand!


 

It's in the JODIL file #62-29777-1572.

 

Cheers

 

HANS


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