Convert .308 to 7.62x39?

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05-13-2016, 05:17 PM
Battlehawk1025

Convert .308 to 7.62x39?

Hey Folks,
Long time no posting. Long story short I have a 308 barreled action I purchased off a friend. I believe its model 11 VT. Any way I have plenty of 308s laying around. I was looking to convert it to a 7.62x39 and use it as a inexpensive pinker.

I know I have to change the bolt head or extractor(one of the 2). But my question is it "safe" to just use one of those chamber adapters in the factory barrel? I have seen mixed reviews on them. Or am I much safer just to purchase a prefit 7.62x39 barrel and go from there?
Any experiences and other suggestions would be helpful.
Thanks!!
05-13-2016, 06:22 PM
RustyShackle

The 7.62x39 actually uses a 7.92mm diameter projectile FWIW.
05-13-2016, 07:04 PM
futurerider103

Many just cut the chamber for the x39. I bought an X-Caliber barrel. But the .308 bolt head will work with the sss enhanced extractor kit.
If I wanted to do it cheap I'd just have Jim at apachegunworks do a 7.62x39 Green Mountain barrel from a .308.
Many shoot the x39 out of the smaller .308 barrel with no problems
05-14-2016, 10:45 PM
teebirdhyzer

I built one for my father in law a couple of years ago. We converted a factory .308 to 7.62x39.
I got the new bolt head and if I remember correctly we ended up using a .22-250 factory DBM factory magazine which works perfect.
We ordered one of the chamber adapters and that is what he is using to this day as his standard deer hunting rifle. Has put hundreds of rounds through it with no issues. Just please understand that if you are building it to shoot the crappy cheap milsurp ammo that is out there I am sorry to say you will most likely be dissapointed. That ammo is so terrbly out of spec that in his rifle 25 to 50% of evey lot he has will not even close in the chamber. The automatic rifles designed to shoot these rounds have loose and sloppy chambers and actions and do not have to have ammo that has tight tolerances. Because of this, the ammo is not made to the same standard as the stuff we shoot in bolt actions. We ended up having to either buy factory ammo, or reload for his...which is better anyway. Just wanted to throw that out there.
05-17-2016, 12:24 AM
Battlehawk1025

Teebird
Exactly what I was looking to do. Except for the crap mil surplus ammo. Worst ammo I may plan to use is probely brown bear or tula. I know it's not the best but do you have any experience with the factory steel case?
I have the factory scout in 7.62x39 that I sold to my brother. That think pretty much eats anything.
05-17-2016, 07:44 AM
Robinhood

Do not take my word for it bu I've heard several people say that a 308 bore will eat the surplus 7.62x39 rounds. The reamer is different for the 308 bore than it is for the 311 one according to Dave Kiff.
05-17-2016, 09:54 AM
earl39

My AR barrel is 308 and after replacing the hammer spring and firing pin it goes thru the Russian stuff just fine. You might want to leave your firing pin protrusion at .050.
05-17-2016, 01:18 PM
Newtosavage

Quote:

Originally Posted by RustyShackle

The 7.62x39 actually uses a 7.92mm diameter projectile FWIW.

Not always. My Savage model 10 "Scout" has a .308 bore and shoots everything I feed it (including .310 and .311 surplus) into tiny little holes.
05-17-2016, 10:43 PM
RC20

Quote:

Originally Posted by RustyShackle

The 7.62x39 actually uses a 7.92mm diameter projectile FWIW.

That would be incorrect . 7.92 is the Mauser Cartridge (.324 caliber ), Russian is 311 or so depending on the random Russian quality.

You can shoot 303 bullets and be quite close.
05-17-2016, 11:16 PM
RustyShackle

Quote:

Originally Posted by RC20

That would be incorrect . 7.92 is the Mauser Cartridge (.324 caliber ), Russian is 311 or so depending on the random Russian quality.

You can shoot 303 bullets and be quite close.

.324 is ~8.22mm by my quick math.

"Russian is 311 or so depending on the random Russian quality." Well that could be, but have you put a micrometer on some of the surplus stuff, .001 over is moderately common in some stuff? Actually IIRC 7.92 was spec on a lot of the rusky stuff. 7.90 would be .311 if my math is right and what I guess the point I was trying to convey, is, that you might experience higher than normal pressures due to the larger projectile size. Take it for what it is and decide accordingly if it will work for you. I just wanted less knowledgeable folks to understand that the x39 isn't .308 diameter.

There are plenty of online resources for information regarding the 7.62x39 in the .308 bore

And here according to a (combloc) drawing is showing the 7.92mm diameter. http://forum.valka.cz/files/d7_62x39.jpg
05-17-2016, 11:20 PM
futurerider103

I know that the diameter is different from the x39 to the .308 but if the manufactures gunsmiths and lawyers said that is going to be ok and is been done for years I'd say is safe because you know they aren't going to risk a negligence lawsuit.
05-18-2016, 04:06 PM
Newtosavage

FWIW, I've mic'd no fewer than five completely different brands of 7.62x39 factory ammo, both US and Russian, and I came up with three distinctly different diameters from .309 to .311.

Some of the Russian stuff was actually smaller than some of the US (Winchester) ammo.

My rifle didn't care. All went into the same fat hole at 100.
05-18-2016, 04:55 PM
RC20

Quote:

Originally Posted by RustyShackle

.324 is ~8.22mm by my quick math.

"Russian is 311 or so depending on the random Russian quality." Well that could be, but have you put a micrometer on some of the surplus stuff, .001 over is moderately common in some stuff? Actually IIRC 7.92 was spec on a lot of the rusky stuff. 7.90 would be .311 if my math is right and what I guess the point I was trying to convey, is, that you might experience higher than normal pressures due to the larger projectile size. Take it for what it is and decide accordingly if it will work for you. I just wanted less knowledgeable folks to understand that the x39 isn't .308 diameter.

There are plenty of online resources for information regarding the 7.62x39 in the .308 bore

And here according to a (combloc) drawing is showing the 7.92mm diameter. http://forum.valka.cz/files/d7_62x39.jpg

Got it, and that would be correct, 312 is actually 7.92. 7.92 Mauser is actually 8.22 mm (newer one, older one 8.08). All that futzing with number, go with bullet OD and stop the nonsense I say!

Definitely not 308 bore, but then 308 through a Russian 7.62 is not an issue (other than accuracy) 7.92 Mauser for sure would be. 303 which is .311 would be fine as well.

For what its worth, a lot advocate 303 through a Model of 1917 30-06. I would be very cautious at upper load levels with that setup. Bore is acauly a bit tighter than 1903 due to the lands and grove design.