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Ruger 7.62x39 rifles bore size.

2916 Views 3 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:

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
1 - 4 of 4 Posts
I think Davidsons is giving bad info. Somthing does'nt jive with my info. Both , Sierra and Hornady reloading manuals indicate a ..308 bore diameter for the mini-thirty. Perhaps brand new models have .311 bore but older models do not.Too us Reloaders of this fine cartridge, it would be of intrest to know serial #s as to the larger diameters introduction. It was my understanding that bullet makers tried to cover both bore diameters with the .310 bullet. Bottom line, slug your bore before handloading for the mini-thirty!!

the Rugers have the same bore as all of their other .30 chamberings.

load 'em with lighter .308 weights and they shoot just fine.
Anyone have any experience reloading with 110 grain bullets in 7.62x39?
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