I read a post a while ago about someone using .311 bullets in their CZ 527 carbine in 7.62x39. Is this a good idea as i understand that.310 is the upper limit on bullet diameter in this caliber. I see the bullet selection is much better in .311 with some nice 150gr. like the Sierra Pro Hunter spitzer. Can you use these also in an SKS? I haven't slugged my bores so i'm asking here. Thanks for any info.

Slug the bore first. .311" bullets in a .308 bore could cause excessive pressure before the desired velocity is attained.

The standard bullet of the 7.62x39 is .311. AKS, SKS, and AR15s all use the standard Russian bullet diameter of 311. You may be confusing the 7.62 as meaning 30 caliber, ala 7.62x51(308 Win). If the rifle is a factory chamber of 7.62x39 then most likely it is made for .311 bullets. Adding to the confusion is the popular wildcat called the 30x39, which is the 7.62x39 setup to accept .308 diameter bullets.