303 British (312) in 7.62x39?

black_hog_down · April 6, 2018, 02:56 PM

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?

condor bravo · April 6, 2018, 03:10 PM

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.

black_hog_down · April 7, 2018, 05:41 AM

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.}

Road_Clam · April 7, 2018, 07:30 AM

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.

T. O'Heir · April 7, 2018, 12:32 PM

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.

Russell P · April 8, 2018, 08:34 AM

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.

black_hog_down · April 8, 2018, 01:04 PM

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.}

April 6, 2018, 02:56 PM	#1
black_hog_down Senior Member Join Date: May 13, 2016 Posts: 111	303 British (312) in 7.62x39? 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?

April 6, 2018, 03:10 PM	#2
condor bravo Senior Member Join Date: August 23, 2014 Location: Nevada/Ariz/CA Posts: 1,753	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. __________________ Ouch, the dreaded "M-1 thumb", you just know it will happen eventually, so why not do it now and get it over with?? Last edited by condor bravo; April 8, 2018 at 01:59 PM.

April 7, 2018, 07:30 AM	#4
Road_Clam Senior Member Join Date: November 21, 2013 Location: New Hampshire Posts: 1,695	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. __________________ "To be old an wise you must have been young and stupid"

April 7, 2018, 12:32 PM	#5
T. O'Heir Senior Member Join Date: February 13, 2002 Location: Canada Posts: 12,453	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. __________________ Spelling and grammar count!

April 7, 2018, 05:41 AM	#3
black_hog_down Senior Member Join Date: May 13, 2016 Posts: 111	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.}

April 8, 2018, 08:34 AM	#6
Russell P Member Join Date: April 28, 2017 Posts: 56	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.

April 8, 2018, 01:04 PM	#7
black_hog_down Senior Member Join Date: May 13, 2016 Posts: 111	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.}