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PostPosted: Fri Sep 03, 2004 5:50 pm 
This question refers to a possible way to convert a Mosin Nagant rifle in 7.62x54r to 7.62x39 without rebarreling.

The two advantages for this would be cheap new ammunition and reduction of recoil, especially for carbines like the M38, M44, and M91/59.

There are "chamber adapters" available for such conversions. Why couldn't one:

Obtain a chamber adapter for converting 7.62x54r to 7.62x39

Have a gunsmith turn the rimmed part of the adapter off, so the adapter sits flush in the chamber with the barrel breech face

Silver solder the chamber adapter in the chamber

Run a finishing reamer into the new chamber to true up the new chamber with the barrel throat/leade

Silver solder a reducing washer in the bolt face recess, something that would reduce the bolt face recess from .564" to .446, or whatever the precise diameters are

Heliarc a bit of weld on the extractor hook, and reshape to permit proper extraction

Put a spacer in the back of the magazine

Do whatever to the magazine lips to support reliable feeding

Given that rebarreling is not only prohibitively expensive, I note that barrel blanks with a .310" bore are not readily available in the US, and that having the original barrel (if the bore is good) with its original markings would be part of the fun.

Does this sound nuts?


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PostPosted: Sat Sep 04, 2004 12:30 am 
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That's a lot of work to turn an inexpensive but fairly accurate rifle to an inexpensive poor shooting rifle.

The list you have is doable, but will never get past the problem of a long smooth bore throat getting from the 7.62X39 slug to the chamfer at the champer end of the 7.62 x 54. Also the 7.62 x 39 slug is actually a few thousandths larger and may lead you into an unsafe pressure situation.

If I were doing this, I'd see about pulling back the barrel to get the chamfer in the right place for the 7.62 x 39 and then do the chamber filler and the rest of the list. In any case you need to measure the ammo and slug the barrel to check size. You may need to lap out the barrel to keep it safe.


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PostPosted: Sun Sep 05, 2004 2:20 am 
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As cheap as the guns you are wanting to convert are why waste the time? Ammo is also cheap for both also. you can get a 7.62x54r bolt gun for 80.00 and 400 rds of ammo for50.00 that should include 10% over cost to dealer and shipping. add another 160.00 and get a sks and 500 rds ofammo to go with it. and still have some gas money for the truck to go shoot . you cant get a good .22 for that price hardly. If you still continue good luck and show a picture or two.


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PostPosted: Sun Sep 05, 2004 11:38 am 
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Location: Chino [Flats], Ca SSR
It might be an interesting project to do yourself but paying a gunsmith to do it would likely cost more than a new commercial rifle.

I would stay away from silver soldering anything as it is a high temperature process that will affect any heat treating present and could well amount to uncontrolled heat treating (or annealing) itself.

jpfalt has already addressed the issue of the long freebore. Both cartridges use a nominal .311" bullet so bore diameter should not be a problem. In fact, much of the 7.62x39 ammo I have measured (I am working on a 7.62x39 project myself) has bullets of .310" diameter to as small as .308" diameter. The standard 7.62x39 chamber is designed to swage oversize bullets to bore size so even a .308" barrel chambered with such a reamer will adequately handle standard 7.62x39 ammo.

I am not familiar with the details of a M-N but normally for a project of this nature, I would set the barrel back enough to get virgin material to chamber the new cartridge. In this case, that would amount to at least 1.6" (enough full turns for the sights to be in the right place). I cannot say whether there is enough material in the barrel to allow this.

After taking care of correctly chambering, you would have to address magazine function and proper feeding. The 7.62x39 is about 1/8 inch smaller diameter than the 7.62x54. You would probably have to shim the magazine narrower to maintain a reasonable relationship between consecutive cartridges; if you didn't, they could be almost side by side in the magazine. This would require narrowing the follower and spring also. Without a sample rifle at hand, I won't even guess about making it feed successfully.

Overall, I would say it is a challenging project for a gunsmithing student but not something to pay someone else to do. You could probably find a 7.62x39 bolt rifle new for less than it would cost to pay someone to do this project.


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PostPosted: Sun Sep 05, 2004 6:45 pm 
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Location: Mid Tenn.
George, does anyone make a 7.65 x 39 bolt rifle these days? I know that "made in China KAR-98 Mauser look-alikes" were once available in the pre-Clinton/Reno years, but are they being imported today?

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PostPosted: Mon Sep 06, 2004 9:29 am 
Thanks for all of the replies. I'd forgotten to consider the freebore issue, which would certainly affect things and make such a project impractical for my uses. Thanks again for the help!


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PostPosted: Mon Sep 06, 2004 10:47 am 
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Location: Spangle, WA USA
Why not set the barrel back and rechamber? The bolt face can have a bushing soldered in using plumbers solder without getting to hot, have done this a few times. The extractor can be welded with a torch and heat treated with the same, use spring steel for welding rod and don't over heat ( use nutral flame).


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PostPosted: Mon Sep 06, 2004 11:41 am 
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Location: Chino [Flats], Ca SSR
in 7.62x39 from CZ-USA for a reasonable price. Check out this page at CZ-USA and scroll down about 2/3 of the page. Interarms appears to be defunct but Charles Daly is importing the Mini-Mauser actions and rifles. Here is a reference on the Gun Parts Corp website. They are a lot more expensive than the one I bought and it makes the CZ look like more sense than building one from a mini action. The only advantage I can see with building one yourself is you could chamber it with an accuracy reamer instead of the "shoot any size ammo" chamber that is standard.

Here is an article about the CZ by a happy owner.


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PostPosted: Mon Sep 06, 2004 6:46 pm 
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Thanks, George! I appreciate the links.

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PostPosted: Tue Sep 07, 2004 1:43 pm 
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Al,

If you plug the gas port the SKS becomes a bolt action rifle.

I have thought about putting an adjustable restrictor in the gas port to get away from the SKS throwing brass all over in a 50 yard circle.


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PostPosted: Tue Sep 07, 2004 7:17 pm 
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True, but it is still butt ugly when compared to a Mauser KAR98! LOL!

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PostPosted: Fri Sep 10, 2004 7:45 am 
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..............For the shear joy, pain, suffering, elation, and hands on creating, I'd say the conversion of a 7.62x54R to 30 Rooski Shortski would be a soul filling experience! There are easier ways that are easier and just as satisfying.

Image
This is a small ring Mauser I built, chambered to 7.62x39. The barrel came from GPC for $99, the stock was from Boyds for $69 and the action was one of a BUNCH of stripped recievers a friend and I bought from Century many moons ago for $4.95 each. To complete the actions we bought parts from Springfield Sporters so total action cost was $70.

Image
For the $99 to GPC you get a magazine blocker (shaped piece of nylon) a follower (plastic) and follower spring (looked like it was stolen from a AK magazine). I chucked the plastic follower and cut down the steel one, soldering on a brass strip to bias the skinnier cartridge case to the right against the feed rail.

The nylon mag spacer would move forward under recoil so as to bind up the follower. I drilled a hole through the rear of the mag housing into the spacer block. No more problem.

Image
I cut off the old boltknob and MiG welded on a replacement $5.95 from GPC and D&T'd for the Williams peep sight. The front sight ramp was a piece of keystock I filled to shape and serated the ramp with a thread chasing file. Then I cut a dovetail to take a Lyman #17 insert type front sight. It was soldered to the barrel.

So for what, less then $300 I made what I consider a very attractive little sporter. I must confess I was less then overjoyed with the appearance of the barrel. Both inside and out. The countour looked like it had been done by 2 different guys, both starting at either end and working toward the middle. That whoopsie had to be carefully turned smooth. Internally the bore appeared to have been reamed with a rotary file as the bore was 'naked eye' rough. The grooves though were smoothly cut rifled.

All that negative aside, the thing shoots way beyond it's initial appearance and will shoot like a house afire. The GPC barrel is available for small ring and large ring Mausers. It has a .300"x.308" bore-groove. A real neat deal is a load I stumbled across that fit's it to a T. That's 28.0grs of surplus 4895 (full caseload) and the Lee C312-165 gr cast slug. Velocity is 1950 fps and it'll eat the 10 ring out at 50 yards.

Since I doubt GPC has any of these small rings around, you could use a Turkish M38, M1903, or any of the fairly inexpensive M98 type Mausers out there and maybe offset a bit of the additional expense by utilizing the issue stock or selling off all the military hardware and just using the action.

Best,
Rick

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