7.62 x 39 .310 ammo in .308 bore

People have shot .3092" diameter Lapua 185 grain FMJRB match bullets in barrels with.3075" groove diameters without issues.

SAAMI specs for most 30 caliber bullets are .306" to .309". Groove diameters .308" to .310.

USA military 30 caliber bullet diameters range from .3070" in service ammo to .3086" in match ammo.
 
Last edited:
If you already knew what the internets said about it, why did you bother asking?

FURTHER evidence is that anytime anyone offers a contrary opinion, you immediately dismiss it saying this guy, that guy said this.

It's fine to be confident, but at least try to see the merit of someone's experience, even if it differs from yours.

Sure. Sometimes .311 bullets go down a 308 bore. But why would you? It would be like putting race gas (unleaded) in a geo metro. Sure, it won't hurt it... But... Why...

More like putting diesel in a gasoline vehicle. I've known people who have (farm hands at a small farm) and the car, once you get the diesel out, runs fine. Other people, same thing, no matter what they did and how many times they flushed it, the car wouldn't ever start again.

You may live... But why? Would you play Russian roulette because you have a 1 in 5(1 in 6 or 8 if you're lucky) chance of surviving... Same deal here. You may loose your face. You might not. No one can stop you.

Sent from my SM-G975U using Tapatalk
 
For what it's worth, competitors getting best accuracy with centerfire rifles use bullets at least. 0004" larger than the barrel's groove diameter.

When the British commonwealth started using 7.62 NATO M80 ammo in their fullbore long-range rifles, they had to use barrels with .3065" groove diameters for best accuracy because most bullets were .3070" diameter.
 
Joeanybody,

If you look at government bore specifications for 30-06, the groove diameter and the bore diameter are ±0.0015" with no change in the ammunition. Indeed, in extreme cases, you hear of people getting their 7mm (0.284") and 30 cal (0.308") bullets mixed up and firing the fatter slug in the narrower barrel and not having the gun blow up. They do get high-pressure signs and you can't count on that being safe in every instance and the accuracy of such ammunition is terrible, but it is possible to do.

The reason for the above is the copper jacket has a yield strength that is a threshold value and that is the principal source of resistance to the bullet entering the throat and getting swaged into the rifling. Once there is enough pressure to surpass that and initiate the swaging, the added force requirement a small difference in diameter contributes is relatively less.
 
I read somewhere that a long time ago someone rechambered a 6.5mm Arisaka rifle for .30-06 but didn't change the barrel. The story goes that it kicked like a mule but didn't blow up. Not that I'd recommend something like that but... :D

If my info is correct that rifle is now in the NRA museum.

Tony
 
I had one of the first Mini 30’s and loaded it with .308 bullets and typically after some trigger work it shot 1.75 MOA at 100yds. Then I tried some Russian ammo, Kabang. Boy that thing had some snort. At the time I was a reloading newb and had no idea there was a difference in the bullet diameters. I thought 7.62 was the same for any .30 cal bullet. After shooting about a thousand of the cheap Russian rounds through my rifle I learned why they seemed ‘hot’. Didn’t seem to hurt my rifle and I shot it a lot over the years. I did read something years later about the bore in my Mini 30. Supposedly the bore had a tapered diameter that squeezed the bullet down towards the muzzle. Not sure how true that is, but maybe Rugers way of making it so the gun could shoot all diameters of .30 cal bullets.
 
You must log in or register to reply here.
Back
Top