Thread: 7.62x39 rifling groove diameter

My Ruger ranch rifle has a .311 diameter grooves according to the internet.
I have projectiles that are .310. It seams most projectiles for this caliber are this size. I have two neck resizers .308 and .311 (collets) in the Lee dies.

I have a couple of questions if someone would be kind enough to answer.

1. Should I try and find and use .311 projectiles (303)?
2. If using .311 collet with a .310 projectile will the projectile be held in the neck of the case well enough?
3. Should I try the .308 collet and try and get a pill in there. Hopefully, not damaging the brass case?
4. Any information you have regarding reloading this caliber would be appreciated. I was going to use CFE black. However, I have to travel to Auckland to get it. A local is selling ADI AR2207 powder. And it $20 cheaper. Any thoughts to save me time and hassle would be great.

5. Any ideas on bullet creep and the distance off the lands. For improving accuracy.

To anyone that answers my questions. Thank you in advance for sharing your knowledge.

Kind regards, Brent

Gidday Brent

My Howa 7.62x39 (since sold) shot just as well with .308 projectiles as .311 ones, both better than MOA. You'll find that as long as the projectile doesn't have a "sharp" radius on its base it'll seat just fine with either collet. Consistent neck tension is quite important to producing good reloads, but it doesn't really matter how much it is as long as it is consistent (and not so little that projectiles move).

CFE Black goers really well in this cartridge, I got 125 gn projectiles going at 2500 fps quite easily. I have some CFE Black left over that I'd sell (or you can have a wee bit to try if you like). PM me if you want to go down this path.

Cheers

Hi tentman, thanks for your reply.
I’ll try some .310 projectiles first and have a play with other sizes.
What part of the country are you in? I don’t think anyone with send powder😋

Uses the ssshhhhhh I won't tell if you don't tell shipping method.

Originally Posted by Slug

Uses the ssshhhhhh I won't tell if you don't tell shipping method.

Yeah - or this . . . .

I'm in Invercargill but will be in your neck of the woods in early Nov so could deliver . . . .

Originally Posted by Tentman

I'm in Invercargill but will be in your neck of the woods in early Nov so could deliver . . . .

Thanks Tentman, sounds great. How much powder do you have and how much would you like for it?
I can meet you in town, or where ever you will be. Can we send personal messages to swap details? Cheers for your help.

.310" will completely seal a .311" bore when fired as the bullet displaces slightly when the lands push into it, causing it to fill the grooves. Displacement varies from .001" to .003" depending on the number of lands and their width.

What he said but with a picture

I put the 308 expander ball in my set of dies and left them there..... we loaded all sorts of .308 projectiles with good results....did try the 310 but not huge difference
to my way of thinking...7.62x39mm is a 150 yard game cartridge...it just runs out of steam too quick beyond that so accuracy of 2" at hundred is perfectly acceptable,no need for any better ,solid chest shots and deer fall over.
try some speer 130grn hps and nosler 125grn ballistic tips....

I'm with Micky Duck on this re accuracy what you are getting is fit for purpose with that cartridge. I have no intention of reloading for my howa as I have a supply of steel case ammunition and 1 to 11/2 inches is fine. It's not a target rifle after all.
Barnaul is or has dried up but there is still a lot of Chinese ammunition around and hornady steel case with the sst.
Just my 2c

Just an update. I’ve just made up some dummy loads. The .311 neck sizer dis not give enough neck tension. I could push them in by hand😋. .308 neck sizer I could just seat the bullet. The shoulder didn’t seam to deform.

I did notice the .308 collet got pushed up and the last stage of pushing the handle down. Even when I reset the collet and backed the die off a bit. I’m assuming the collect was pushing the bottom of the case.

Dies anyone know why it was doing that?

I may get a gunsmith to shave the .311 collet down to maybe .309 to make seating the projectiles better. I think there should be enough neck tension.
I’m thinking.310 will maybe give to much neck tension.

Thanks for all your advice and help, Brent