I used a 123gr Fusion ammo this year. I have found a 150gr shell from Corbon. They use a Sierra Spizer bullet. The diameter is listed as .308. The barrel on my rifle is listed as .310 from CZUSA. Is there a potential issue here with the bullet being slightly undersized?

Shoot it and see?

I just measured some .308 bullets and they measured .3088"-.3086".

If your barrel measurements are made between the grooves, the bullet should fly & stabilize because the lands will measure less.

why would they say it is 7.62 if it is not a 7.62 which is .308 ? that is interesting.

NWBama,

the 7.62x39 is not a true 308. it's bullets are .310-.311. if you look in the sierra manual you will see the bullets that are listed for the 7.62x39. try the .308 bullets but my guess is they will not be as accurate as the true 7.62x39 bullets. the difference in the 7.62 and .308 is the 7.62 is metric and the .308 is U.S. measurements. i hope this helps.

In a rifled barrel, the distance is measured between opposing lands or grooves; groove measurements are common in cartridge designations originating in the United States, while land measurements are more common elsewhere. It is important to performance that a bullet should closely match the groove diameter of a barrel to ensure a good seal.

308 bullets work in my 7.5x55 too although I wasn't completely convinced until I miched some factory ammo and Hornady bullets.