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1928 Lower In 1927 Tommy


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#1 marek

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Posted 16 September 2005 - 10:26 AM

sad.gif Anybody have a blueprints how to modify 1928 lower to fit 1927 gun?? Thanks for a help.
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#2 TommyGunner

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Posted 16 September 2005 - 11:04 AM

I hear that Doug Richardson (see FAQ for contact info) has a booklet that explains the process. If you understand the concept you can pretty much figure it out though. You would have to mill a groove down the inside of the Tail for the semi firing pin to travel (refer to your semi frame) and would have to mill a notch off of the front of the frame to meet up with the Jog in the semi reciever...don't take it off the reciever or it will weaken the drum slot! Take a little off at a time to ensure the best fit. You will also have to shim the internals to line up with the bolt properly. This is also easy to figure out with both frames and the semi internals to reference. If you want to be a cowboy go for it...is easy enough. If you need more information to be comfortable with it and try yourself...get Doug's book. If you think it is too much for you there are competent gunsmiths on this board that can perform the work for you. PK and I come to mind as Thompsonsmiths...but there are others that can do it I am sure. wink.gif If you have some basic machining skils you should be able to be a cowboy and just wing it though. BTW...whatever you do...we all like pictures!

Best of luck,
Damon
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#3 kilroyjones

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Posted 16 September 2005 - 12:13 PM

I asked the same question a few weeks back. PK told me about the Doug Richardson manual, and it was well worth the money. The manual is titled "Thompson New Production Semi-autos".

If all goes right, I plan on milling my 28 frame tommorow. If all goes wrong I plan on ordering another 28 frame tommorow. blink.gif

The manual gives very precise and clear instructions with dimensioned drawings, so I think even an amatuer machinist like myself can do it

KJ

PS If you order the manual make sure you get Doug's latest catalog. there is a lot of useful info in there also.
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#4 full auto 45

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Posted 16 September 2005 - 05:19 PM

QUOTE (kilroyjones @ Sep 16 2005, 12:13 PM)


If all goes right, I plan on milling my 28 frame tommorow. If all goes wrong I plan on ordering another 28 frame tommorow.

AAAAAAAAAAAAAAAAGH! mad.gif
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#5 kilroyjones

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Posted 16 September 2005 - 06:48 PM

QUOTE (full auto 45 @ Sep 16 2005, 05:19 PM)

AAAAAAAAAAAAAAAAGH! mad.gif

Your anger is because a 28 frame is being cut for a Kahr?

You will be glad to know I made the initial .375" x .10" cut tonight. Everything fit, so tomorrow morning I will cut the firing pin channel.

I think it will look great once it is finished with chrome plating and an Aimpoint sight bolted to the top rolleyes.gif

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#6 TommyGunner

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Posted 16 September 2005 - 07:06 PM

QUOTE
I think it will look great once it is finished with chrome plating and an Aimpoint sight bolted to the top 


He, He...don't forget the brass catcher and tactical sling! tongue.gif

Send in some pictures of that bad boy when you are done! What other mods are you doing? What type of finish? Details! What if we had a post of all the DIY gunsmithing photo's of these custom semi's. Would be great to see everyone's work!

Damon
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#7 kilroyjones

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Posted 16 September 2005 - 07:22 PM

Right now my list of things to do:

Turn the cocking knob down to a more authentic shape ( yeah I know I can buy one, but I want to DIY)
Set the comp back over the barrel for a shorter look
Install a Lyman adjust. sight
Lengthen the forward grip mount by 1" or so and have Dan make a custom vert. grip (to help make the barrel look shorter)
Connect the full auto selector to work as a bolt hold open (still thinking this one over, have a few ideas on how to do it)
Mill the drum divots into the frame
Nickle the drum rotor (because this gives me a good reason to buy a plating kit)
I would like to finish the gun and drum in a Colt royal blue style.

I just wish someone made a nylon stock set for the Thompson. That and the chrome plating would make it the perfect gun to take along on frog gigging trips.
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#8 TommyGunner

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Posted 16 September 2005 - 07:54 PM

Kilroy,

Sounds like a pretty nice project!

Turning the cocking knob down...I would just get a new one on this. You can't get the proper look turning down a chese grater...just something close to a smooth knob. But hey...knock yourself out.

Setting the comp back is not too difficult...just need to make a ring to fix the cutts to since the barrel diameter is smaller than the end. If done right is pretty invisible.

Install a lyman sight....this is a bit trickier than the others. The rivet holes have to be countersunk on the inside of the reciever and the head has to form into the holes on the sight flush. I am cautious reccomending this one unless you have experience. Not to offend but you may want to send that one out to someone who is set up and has done a few.

Lengthening the gripmount and foregrip is interesting...would like to see how it comes out. Were you planning on making a custom gripmount? If so PK makes beautiful gripmounts and perhaps he could make you a custom one. Can this be done witout lenghtening the gripmount...I did not think into it to far but seems the screw hole would need to be relocated perhaps.

Bolt hold open...you will need to relieve a notch in your internals that block the selector from passing through. You will also need a custom pawl and springs. You can customize the existing pawl with a pin and washer soldered on but we make a milled pawl for such purposes...the engineering is done and springs figured out. It will save you so much time in fiddling it is really the way to go. The spring/pawl setup is a bit tricky.

Drum Divots...these are not a standard size. You can buy a corner rounding ball mill and entropolate(sp?) both divots with one standard tool if you have a cnc mill. If you do not have a cnc mill you will need to have 2 cutters made...one for each size divot. Just about everything on a Thompson is an odd size...makes tooling up a challenge.

Nickel the drum rotor...don't for get the frame internals (except for trigger) and the slide latch! Let me know the details on the plating kit and how well it works if you do not mind. If it works good...I will send you some work if you like.

Colt royal blue = rust blue...you can buy the kit at Brownells for $30-$40..cant remember. Dan Block used it recently with some really nice results...perhaps you could get some pointers from him on that.

Nylon stockset and chrome plating for frog gigging...good idea! You could stun them and locate them in one move with the reflection of the chrome and then wack em with the nylon buttstock! laugh.gif

Sounds like you got it pretty bad!

Damon
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#9 kilroyjones

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Posted 16 September 2005 - 09:18 PM

The cocking knob may have to come from Doug Richardson. I still might try to turn the old one just to see what happens. I am just to curious for my own good

I talked to Doug Richardson, and he gave me some good advice about the barrel/comp. Basicaly what you have already said about making a ring etc.

The Lyman sight is something I am going to experiment with. I figure on taking a few pratice shots on scrap metal. If I can't get the results I want then it will be sent out to a professional.

There is a thread I started a few days ago about the lengthened grip mount. Dan replied that he had made one once before. He said he used an original mount that was cut and a spacer was welded into the mount.

On the bolt hold open, what is the price for milled pawl and spring?

Divots may be cut close to but not actual size. I will have to study the print when I get to that point

The nickle plating kit is sold by Texas Platers or Caswell. It runs around $40, just a power supply and some solution. You will need to Google for the address, I don't have it available right now. The kit is for electroplating, but I have read several articles that gave the kits good reviews.

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#10 PK.

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Posted 17 September 2005 - 12:05 PM

A couple of minor thoughts:

The radius of the cutter for the drum slot chamfers is the same, front and aft.

“Colt Royal Blue” is a term applied to the finish typically seen on the Python and other higher grade custom shop products. It is a high polish salt blue. I do not believe this term was used prewar, but I may be wrong.

If you are going to install a Lyman sight on a new 27a1, it is best to use rivets having the 4mm thread on one end and the proper stem for the sight on the other.

FWIW

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#11 kilroyjones

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Posted 17 September 2005 - 12:57 PM

PK, I believe you are right about the Royal Blue. It was the best way I could describe the finish I was wanting. Most of todays guns are finished to look more black. I was wanting something with more of a real blue color.

The rivets idea sounds good. I plan on making sample plates of the same thickness as the sight and receiver. Then pratice riveting them together until I am either satisfied or fed up.

KJ

ETA: A picture of the frame and internals after being milled. (Die hard Thompson fans look away)

user posted image
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#12 Zamm

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Posted 17 September 2005 - 06:49 PM

kilroyjones'
That's some darn nice work...
I think you will do well!
Please do post on the Nickel Plating set-up.
Sounds kind of lite in price, so I'm curious how the results come out.
If it's good, I'll get me one too!
Best, Zamm
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