.310 Bullets in a .308 Barrel- Problems?

[jasonprox700]

I was wondering if shooting .310 bullets (7.62x39) through a .308 barrel would be work?  Would there be too high of pressure?  Shooting the .308 bullets would give me more to pick from for reloading.  But, I would also like to buy some of the cheap surplus ammo for plinking and what not.  Is the scenario I am thinking about doable?

[kyelkhunter3006]

You should be ok.  Honestly, more barrels have enough variations in the bore dimensions to negate any ill affects.  For example, I called the Browning service department once, trying to find out the outside muzzle diameter of a rifle barrel.  The tech told me that the bore diameter ranged between .308-.310.  I told him that I wanted the outer dimensions, not the inner.  I thought it interesting that the dimensions allowed for so much variation.

[jasonprox700]

That is kind of what I assumed.  I like to reload, but about the only bullets I can find are 125's.  I've heard that with the .308 bullets in a .308 barrel, this little round can be very accurate.  That is what I am looking for.  Something that kicks very little, accurate for plinking, and has cheap, factory ammo available.

[yooper77]

Are you shooting a firearm chambered for the 7.62x39 that has a .308 diameter bore or is it a different cartridge?

yooper77

[jasonprox700]

It would be for a gun chambered in 7.62x39, but with a bore of .308.

[yooper77]

OK, I understand, well I don't know if it would hurt or help for pressures or accuracy.

I know RCBS makes dies that have both 308 and 311 diameter expanders.
http://www.midwayusa.com/eproductpage.exe/showproduct?saleitemid=573252&t=11082005

yooper77

[Larry Gibson]

If you work up the load with those bullets it won't be a problem at all. I've shot and still shoot thousands of .310/.311 AK/SKS bullets through numerous .308 barrels out of several different cartridges.  The larger bullet gets swaged down to .groove diameter in the first bearing length of travel. This is early in the pressure curve and if accounted for in the load poses no problem.  Actually many worn .308 barrels will show surprising accuracy with the larger bullets.

Larry Gibson

[R.W.Dale]

What kind of 7.62x39mm?

.308 bored 7.62x39's are actually very rare, The only ones I know of are the very first run of Mini30's.

I suggest slugging your bore before you get too tied up in guesswork.

 I've found that a .310 bored x39 will typically shoot both bullet diameters equally well, my current ar15 and my cz527 carbine were no exception. However, I do have 7.62x39 benchrest rig with a Shilen 1/15 twist .308 barrel that will shoot in the .2's with handloads. In this rifle I wouldn't dream of shooting steel jacketed mil spec fodder

[Brithunter]

Hi All,

     Funny thing I used to have a M44 Nagant made at Radom in Poland which had a 0.308 bore and shot exceptionally well with some green laquered steel cased ammo that had 0.308 bullets. it shot well with soem Copper washed steel cased ammo but didn't like the tadpole squiggle Arabic stuff. it's the way it's loaded that makes the difference.

    One thing that you may find using a larger bullet is a faster build up of copper fouling but unless you go daft with the loads I very much doubt it would cause a problem. Let us know how it goes 

[Bugflipper]

Never had a problem either. I have also loaded a bunch of .312 (32 cal) pistol bullets in a .308 bore without any problems.

[Skillet]

This is interesting to me as I've recently purchased a Remington 799, chambered for the 7.62x39 as a light deer/brush gun for my kids to use. Experimenting with handloads for my gun showed a marked preference for .310 diameter bullets over .308 at the range...
Skillet

[kyelkhunter3006]

Since that gun is manufactured in Eastern Europe, I'd imagine that it's got a .310 bore.....

[mrbigtexan]

i have a range report posted in the rossi forum about this caliber and have listed the actual diameters of many commercial bullets. check it out and keep us posted as to how well it shoots.

[iiranger]

Mr. Ackley re chambered a .30 barrel to 8x57 Mauser. Yes, the .323 bullet was shoved into a .308 bore. Fired it with no problems. Accuracy was crap, but no pressure problems.
In this case, fools were buying ANY  military surplus ammo for ANY military surplus gun... ["Don't all soldier rifles fire the same ammo?" Well, no... right up there with "shoots good, goes bang..." Duh...] Now the 8x57 in an '06 chamber where the case can split,... "loose gas" that causes problems and is DANGEROUS! HOT gas.

You should have no problems with a factory rifle. It is possible, low likely, but possible that the larger bullet might make the neck of the cartridge enough larger to be harder to get into the gun/chamber. With a bolt action and the "camming" of the closing bolt, you probably won't notice. In less "stout" actions, lever, semi auto, pump... then you might notice. luck.

[coyotejoe]

It should be noted that when P.O.Ackley conducted his pressure tests of oversize bullets he reamed the chamber neck and throat to fit the oversize bullets, he was not just cramming 7mm and .308 bullets into a .270 chamber. He fired bullets up to .358" down a .277 bore. He found that bullets far over bore size caused no pressure problems SO LONG AS THERE WAS ADEQUATE CLEARANCE AT THE NECK AND THROAT. Loading oversize bullets in a standard chamber may be dangerous if they are tight in the chamber.