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Ruger 7.62X39 bore size

8829 Views 9 Replies 3 Participants Last post by  Mark
I recently requested information from Davidson Guns regarding the actual bore diameter of the Mini Thirty and Model 77 rifles of this caliber. I'm considering reloading, and had heard different stories on the true bore size. The following was the reply I received today. I thought others might find it interesting as well:

Dear Mr. Phelps,

Thank you for your inquiry at! Ruger's groove
diameter for the 7.62X39 caliber cartridge for either the Mini-30 or model
77's is .3100 - .3115 according to their engineering dedpartment. This is a
compromise diameter designed to shoot either the .308 or .313 diameter ammo
that is available. A .311 diameter bullet would be my choice for handloading
applications if available.

I hope this helps!


Rebecca L. Gridley
Web Administrator
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Were you just posting the information as an FYI for all of us?
that sounds like it would be correct, as its my understanding that the russian 7.62 bore is .310.
Reply to jarcp

Yes, just providing info. I had checked around on the internet at several sites, and everyone seemed to have a different opinion on the Mini Thirty and Model 77 7.62x39. Thought the correct info could help someone else too!

I've never reloaded, but am considering it. Thought this would be a good one to start with. Any suggestions from anyone who has reloaded this round would be appreciated.
Mark. I reload the 7.62x39 pretty often. With the surplus ammo on the market it's not really worth it money wise, but I've done some heavy for caliber loads I like, and I already have the dies so it works out in the long run. What if any questions do you have?
I agree about the surplus ammo, if you are plinking with an SKS. I was looking for a more accurate load for the previously mentioned M77 Ruger rifle. In particular, I'm looking for a good whitetail load. 99% of my shots would be within 150 yards. This is traditionally 30-30 country.

As for your heavier loads, do you find the accuracy improved? Does it reduce the effective range considerably?

Considering the info from Ruger, I'm thinking of going with the .308 bullets, since I have a .308 Win (7.62x51) rifle as well. Think I would have a noticeable degradation in accuracy?
The .308 bullet is a good choice, I doubt you'll notice any degrade in accuracy, as well you have a MUCH broader choice of bullet's to choose from. Have you settled on a powder yet? I've always been pleased with AA 1680 for the 100-120g bullets. If you go up in weight you'll need to get a slower and bulkier powder. As for the heaiver bullets, it's a project to match the ballistics of the .300 Whisper. Accuracy for the time is similar to the .30 carb. and the effective range is reduced to no more than 200 yards. It's a work in progress.....
I see that Cor-Bon has a 150 grain bullet travelling at 2300 fps. I'd say thats pretty dang impressive, if you can hit the broad side of a barn with it. Have you gotten to that point yet, jarcp?
Right now I playing with 180g bullets. in the relm of 1500fps.
jarcp, I found a page you might be interested in (if you haven't seen it already). Checkout They have some pretty interesting info on 125 to 240 grain bullets.
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