303 British (312) in 7.62x39?

B

black_hog_down

New member
Can I shoot 174 grain 312 caliber jacketed bullets in my 7.62x39?
This is a Ruger M77 bolt action. I'm guessing that the barrel is 310. I know that the answer is to slug the barrel... BUT how close do I need to be?
If it slugs at 310? 311?
Also, I only have load data to 150 grains. Surely there's data to 180 out there?
 
The .303 Brit is normally rated as .311 but either .311 or .312 should be fine. The 174 gr might be something else again and more properly used with the Enfield. Factory ballistics for the cartridge are close to the .308 Win.

The 303 Brit not to be confused with .303 Savage which is .308, and sort of like a .30-30. And the .300 Savage is .308.
 
Last edited:
The more I think about it, I think these bullets are just too long. I am looking at the 180 grain RNSP Hot Cor bullets made by Speer.
I can't find information about bullet length.
How do I figure this out without buying some?

{Edit: Please read the board policy on posting copyrighted materials. In this instance, Speer owns the copyright, so you need their permission to post it.}
 
Your most likely not going to get the 174 gr bullet seated deep enough to allow mag loading . You will probably encounter powder compression lockup. I loaded .308 165 gr spitzers and with a mild charge was able to get to mag length depth. I tried 155 SMK's and no go. I used Benchmark powder in x39 with the heavy bullets, actually got good accuracy considering it was my Opap AK47.
 
174 grain FMJ's are too big for the 7.62 x 39. That Hornady(who use .312" for their .303 Brit intended bullets) bullet is 1.263" long. 39mm equals 1.536". There's no proper, lab tested, load data for 'em anyway.
"...guessing that the barrel is 310..." No guessing involved. Ruger uses .311" for 7.62 x 39, now. There's a post about it on this forum from 2015. One of the guys had one and slugged it at .311". Mind you, 1 thou isn't going to make any difference, but the weight and length of the bullet will.
 
I'm fairly confident that the projectile you want to use would be too long. 762x39 already has a reputation for case capacity issues. You probably won't get enough powder for a good load IMHO.

Hornadys data for 150g projectiles are all .308 so no help there.
 
So this page shows getting up to 28.2 grains in the case with a 174 grain bullet and 25.1 with a 210 grain bullet.
http://www.accuratereloading.com/76239.html
If you look at 300 blackout data using a 180 grain bullet, this shows a starting load of 16 grains.

So it would seem there is enough case capacity to load some up? Is it wrong to use 300 BLK load data as a starting point?

{Edit: Please read the board policy on posting copyrighted materials. In this instance, Hornady owns the copyright, so you need their permission to post it.}
 
You must log in or register to reply here.
Back
Top