Semi-Auto Thompson Stock Adapter...

[John Sabato]

Some years ago, either Gun Parts Corp, or Numrich was offering an adapter that would fit the bottom frame of the fixed stock type semi-auto Thompsons, that would adapt them to the M1928 type detachable stock.

They just bolted on and provide the required mating surface for the M1928 type stock. I have not seen them in years. Can't seem to find any online at Kahr, Gun Parts, or Sarco either.

Anyone know where to find one of these stock adapters?

(How about Alanint? I figured if anyone would know Doug, you would know...)

[alanint]

Hi John,
I remember these very well from the old Numrich catalogue. Let me ask my private lists and see if I can come up with one for you.

[alanint]

Hi John,

BINGO! contact them to sell you just the adapter.

http://www.tommygunner.com/pages/par...kits/index.htm

[John Sabato]

Thanks Doug!

[ithacaartist]

Thanks Doug, they were out, last time I checked.

John, they don't just "bolt right on". The butt stock mounting structure of the lower receiver needs to be modified by milling off a bunch of material. The approx. 1/8" tall remaining structure is then drilled and tapped to receive the adapter plate. The adapter plate is pretty simple, so I plan to make my own; the most demanding aspect is to accurately locate the notch for the latch on the stock. Some curves/lines on the bottom of the receiver also need to be changed to make the installation true-to-original in shape.

I thought I was all set to go, armed with a copy of the blueprint of a 1928 and a removable 1928 butt stock with all its hardware. The butt stock arrived, but I found once cleaned up and all the cosmolene scraped off, that it had been exposed to water at one point during its storage and it was rusty on parts of the structure that were not exposed, where the water had seeped in. In addition, the furniture had absorbed the oxide and is stained. This latter part is my problem, as rust stains are very difficult, if not impossible, to remove from wood, once established.

Anybody know of a sure-fire way to bleach out the danged stains? (Oops, didn't mean to hijack your thread!!)

[John Sabato]

Originally Posted by ithacaartist

... as rust stains are very difficult, if not impossible, to remove from wood, once established.

Anybody know of a sure-fire way to bleach out the danged stains? (Oops, didn't mean to hijack your thread!!)

No Hijack since I got my answer from Doug.

I would use electrolysis for the rust on the metal, and would likely try a full strength Lime-Away soak for the rust stains on the wood... After all, you've got nothing to lose... the only other alternative would be new wood ($$$), or a lot of sandpaper and elbow grease.

[ithacaartist]

I haven't applied anything to it until I have some confidence the process will work, or is even feasible. I'm going to try some different stuff in addition to the Lime-Away, experimenting/testing on other pieces of rusty wood; so, stay tuned.

I doubt sanding would do me any good because the staining has soaked into the end-grain. As you can see in the pic, the stain is black, like boiled rust blue. The way the stock soaked it up would never allow you to hit bottom when sanding.

Too bad Kahr is not listing their '28 removable butt stocks as a separate item, but only on the complete carbine, which is available with a removable stock. I would have preferred one of these, anyway, because the furniture would match without doing anything.

I bought this one from a member of the machine gun forum. He had a pristine one, but I cheap-ed out and chose the second best because the color looked better. Maybe I should see if he and I can work something out, if he still has the good one.

Otherwise, as you suggest, I'd need to reproduce the stock. I've noticed that the '28 stock is shorter than the '27--which I already found uncomfortable due to its being "dimensionally challenged" and this would be a chance to avail myself of a super-long '28 style stock, as long as I'mcreating a Franken-Tommy.

[rolandtg]

You might look into Oxalic acid for removing the stains from the wood.
For example: http://www.rockler.com/oxalic-acid-for-wood-bleaching

[rhuff]

A number of years ago I used oxalic acid, an oxidizer, to lighten some weathered wood in an attempt to get back to the original color and grain. It pretty well accomplished what I wanted it to do. I am not sure how it might work for you since the stain has migrated from the cross cut grain upward. I would not rule it out though.

Does Sarco still have 1928 stocks without the hardware? They used to have a ton of it, but the chance of color matching would be a crap shoot.

[ithacaartist]

Originally Posted by rhuff

A number of years ago I used oxalic acid...

Does Sarco still have 1928 stocks without the hardware? They used to have a ton of it, but the chance of color matching would be a crap shoot.

Thanks for the oxalic acid suggestion. (Ironically, I'm limiting oxalates in my diet to slow or stop the growth of a kidney stone--discovered in x-rays of my back to check out my sciatica a couple years ago.)

John Sabato and I have each purchased one from eBay, which is crawling with them. Mine is un-issued, his is the same but I believe it has a finish. There's a nice one listed, looks great, complete with hardware, for $110. Had I seen this one earlier, I would have bought it and saved myself a heap of time and effort.

The hardware for the complete one I did buy turned out to be a little rusty, but only in areas that won't show when installed, or are easy to clean up. *sigh* Funny how projects like this tend to grow in scope due to discoveries along the way. Anyway, I'm going to fabricate my own adapter plate and I'm pretty sure I can pull off the mods the lower receiver needs to accommodate it. I may forgo mechanical fasteners and plug weld the plate on with a TIG welder.

[alanint]

John,

Any luck with just purchasing the adapter for the M1/M1928 interface?

[John Sabato]

Hi Doug
I have seen photos of the Numrich adapter installed and though it bolts right on the semi auto frame, because of the threaded boss on the frame where the non detachable stock is bolted on, the adapter causes the 1928 detachable stock to be noticeably lower from the receiver. I don't care for that look and plan on following David in permanent modification of the semi auto frame to the 1928 dimensions including the mounting surface for the 1928 stock. It may take me longer but will not look like a kludge when I am done.

[alanint]

I can't argue with that. "Look", silly as it may be to some, has always played a central role in what I like and collect.

[rhuff]

Originally Posted by ithacaartist

Funny how projects like this tend to grow in scope due to discoveries along the way..

\

Do I ever know how true that statement is these days. I start a "simple" project that should take a day or so, and three(3) weeks later I am still not finished. It could be an age thing........naw, couldn't be that!!

[sheepherder]

Seller on GB has a new Numrich/Auto-Ordnance buttstock for sale...

http://www.gunbroker.com/Auction/Vie...Item=424789427

Everyone should have a hobby... ...

[ithacaartist]

Too late. Here's what I have so far. I had a machinist do the milling and adapter plate fab, after all, for $180. My only gripe is that he apparently went a few thousandths too far and had to relieve the rear end of the lower enough to remove the bluing in that area. I took he hardware for the stock to GunBlack, in Interlaken NY, were it was cleaned up by an acid dip, then re-blued. I didn't bother with the pitting and simply had them blue right over it. At least my notion that it would not show the damage when installed proved out!

If I had it to do over again, I'd probably do it myself. The adapter plate is simply a piece of 1/8" x 1", and the milling could be supplanted by first sawing out the bulk of the material that needs to go. Next, I'd use a body grinder to get closer, then carefully true it up and finish it off with file work. The placement of the holes is arbitrary, within bounds, so no biggie there--just need to flush off the ends of the fasteners if they protrude into the top, inside of the lower, where they need to avoid the bolt body.

I think my machinist guy would do it again, but I wasn't all that happy dealing with him. He never answered an email, took forever to get to it (then it was completed, overnight) and I got the impression he wanted more $. At least this approach was more economical than sending it to a Thompson specialist, which made the small goof easy enough to swallow...

Originally Posted by sheepherder

Seller on GB has a new Numrich/Auto-Ordnance buttstock for sale...
http://www.gunbroker.com/Auction/Vie...Item=424789427...

Nope, sorry Rich, the one pictured in this listing is the non-removable type for the '27 style. Its front end is curved differently, and you can see on the inside where the cylindrical lug that hangs down from the lower is accommodated, along with the extra meat. I already have two like this--the one original to the carbine, and a new, unissued one without any hardware or finish. It is in better condition than the G.B. offering, and cost me $30. I bought it by mistake,thinking it was what I needed.

[sheepherder]

Originally Posted by ithacaartist

I had a machinist do the milling and adapter plate fab, after all, for $180.

I don't need to tell you that you got robbed. And with an attitude no less.

In a way, I can understand the machinist's attitude. He didn't really want the job, and he wants to make sure you know it, and never come back.

I was working in my shop one day (several years ago) when I heard a go-cart like thing buzzing around. Teen-age neighbor kids, cutting through my 'lower 40' to get to their buddies on a neighboring road. (They policed the area after they had their inevitable 'parties', so I had no complaints). I could hear talking, and engine racing. I finally went out; they had stripped a keyway for the drive sprocket. I loaned them a couple tools to remove the rear axle, took it down and cut a new keyway, gave them a piece of keystock, and they were back in business inside an hour.

They're grown up and moved away, so I never see them anymore. Never knew them really, except to wave when they buzzed by. Go-karts/mini-bikes in Summer; sno-mobiles in Winter.

Lots of people I never knew have helped me out in my life. I'll never get a chance to repay them. But maybe someone else will.

My rant for the day.

[John Sabato]

Originally Posted by sheepherder

I don't need to tell you that you got robbed. And with an attitude no less.

In a way, I can understand the machinist's attitude. He didn't really want the job, and he wants to make sure you know it, and never come back.

Hey Rich... what alternative did Dave have? You have a combo Mill/Lathe in your basement. Some of us are not that fortunate, and have to pay the going rate to those who are equipped for the work...

I plan on the same modification for my Semi-Thompson... I already have the 1928 buttstock. I don't own a mill. So I can either invest the $180 toward buying my own milling machine or a milling attachment for my lather, or pay someone who already has one...

Are you taking in work for free now?

[rhuff]

Originally Posted by ithacaartist

Too late. Here's what I have so far. I had a machinist do the milling and adapter plate fab, after all, for $180. My only gripe is that he apparently went a few thousandths too far and had to relieve the rear end of the lower enough to remove the bluing in that area. I took he hardware for the stock to GunBlack, in Interlaken NY, were it was cleaned up by an acid dip, then re-blued. I didn't bother with the pitting and simply had them blue right over it. At least my notion that it would not show the damage when installed proved out!

If I had it to do over again, I'd probably do it myself. The adapter plate is simply a piece of 1/8" x 1", and the milling could be supplanted by first sawing out the bulk of the material that needs to go. Next, I'd use a body grinder to get closer, then carefully true it up and finish it off with file work. The placement of the holes is arbitrary, within bounds, so no biggie there--just need to flush off the ends of the fasteners if they protrude into the top, inside of the lower, where they need to avoid the bolt body.

I think my machinist guy would do it again, but I wasn't all that happy dealing with him. He never answered an email, took forever to get to it (then it was completed, overnight) and I got the impression he wanted more $. At least this approach was more economical than sending it to a Thompson specialist, which made the small goof easy enough to swallow...



Nope, sorry Rich, the one pictured in this listing is the non-removable type for the '27 style. Its front end is curved differently, and you can see on the inside where the cylindrical lug that hangs down from the lower is accommodated, along with the extra meat. I already have two like this--the one original to the carbine, and a new, unissued one without any hardware or finish. It is in better condition than the G.B. offering, and cost me $30. I bought it by mistake,thinking it was what I needed.

It looks to me as though it turned out fine. It functions(I assume) and the butt stock fits up properly. It looks good to me.

When I start out a project, it ALWAYS costs me more to do the first item, as I am "walking in the dark". After the first one is done, usually I have refined my process and the second item is produced faster and cheaper. You did a nice job.

[sheepherder]

Originally Posted by John Sabato

Are you taking in work for free now?

I lose money on any job I do.

I had posted this scan from the Numrich catalog to someone's thread here once before...But here it is again...