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 mgc 1921 restoration

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Location / Country : usa
Registration date : 2017-07-28

PostSubject: mgc 1921 restoration   Sat Aug 05, 2017 3:27 am

Just picked up a mgc 1921 Thompson. It is missing the stock. Came with 1 magazine with no markings. The wood has a nice old look with very few dents and no worn finish. The bluing is very worn.

It looks like a pin is in the end of the muzzle. The chamber is plugged and the head of the screw holding the plug in is broke off. From what I found online I should be able to remove the screw under the chamber. Then the plug can be removed and replaced with a chamber and detonator for plug fire cartridges. I have a lathe and can make a new chamber and detonator. Does anyone have drawing or dimensions?

The bolt face is uncut. The extractor is missing the hook to catch the cartridge. Should be able to either make a new one or rework the original.

I found real Thompson wood can be made to fit. I am missing the complete stock. Mgc stocks are missing the cross bolt so would like to have the real stock. Has anyone tried fitting the metal part of a real Thompson stock onto the mgc?

Found the real Thompson magazines can be made to fit. The feed lips are different and the catch hole is in a different location. Don't have a real magazine yet to compare to. Is the only thing needed is to cut the feed lips and make a new hole for the catch or is there more to it?

For the restoration I want to keep the finish on the pistol grip and fore grip as long as it matches the stock. For the metal parts all the mold lines and inperfections will be filed and sanded down, then reblued.

Tried rebluing part of the receiver. It turned out a nice dark almost black blue.
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Location / Country : Iowa, USA
Registration date : 2008-11-26

PostSubject: Re: mgc 1921 restoration   Sat Aug 05, 2017 1:30 pm

Thanks for posting up your project!  Please keep us informed of your progress!

I'll try to add a few thoughts, for what its worth, to address some of your questions.

It looks like you have an "import" model, which is why the bolt is non-functional, the chamber is blocked, and the upper receiver area has a small section milled out.

What I think is good news for you, is that it is a model made sometime before 1978, which means it has an "open" barrel.  That means that if you return it to a firing model, it will vent smoke from the front of the barrel.  Models made after 1978 had fully blocked barrels.  I much prefer the older models because of their ability to vent.  

Chamber - I've seen these slugged and pinned in a couple different ways over the years - all can be reversed if you are mechanically inclined and if you own machinist tools, you obviously must be.  The chamber plug will have a recessed groove that the pin sets in to retain the plug in the receiver.  If you remove the pin, the chamber slug can be removed.  The threads for the chamber retaining screw have not been machined into the receiver any of the blocked models I've seen in the past.  You will likely have to cut threads and install a chamber retaining screw.  Some plugs are a pain to remove, but since you have an open barrel, you are on easy street as it can be driven out by inserting a rod or tool from the muzzle end.  

I don't have the dimensions for the chamber/detonator, but someone on the forum probably does.  I recommend vent holes in the base of the assembly if you're going to "fire" this model, since it will vent smoke from the barrel.

As far as returning it to firing, you should also consider fabricating a recoil spring buffer (rubber piece at the end of the recoil guide).  As an import model, yours will not have this piece.

The bolt- looks like you would also need to machine the face of the bolt you have.  At least it hasn't been cut at an angle, like most were.  The extractor is a fixed piece on this type of bolt and really was improved with the later versions which involved a spring design.  

You probably have an original MGC mag.  They had no markings.  The shape of the lips compared to a real mag are quite different.  As you mentioned, the locking lug hole will not be in the same spot.  I believe you will find that a real mag is also too wide in the spine area.  This can be remedied by modifying the receiver slot or the mag spine.  There are variations in MGC receivers and also variations in real mags, so it's kind of a situation where you might have to fit each one individually.  Getting this old model to work 100% with the stick mag usually requires some fitting to get it feeding just right in my experience.

The MGC Thompson was a very popular model and it still is today.  Because of this, parts can still often be found if you need them -  Bolts, chambers, cartridges, etc.  Some forum members here have helped many of us out with items only found overseas. This is a great forum and you've come to the right place for modelgun info.

Best of luck with your restoration!
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