[quote]ok if 7.62x39mm has a .310 diameter bullet and a ruger mini-30 has a .308 bore diameter. then why is the mini-30 chambered for 7.62x39mm???? wouldnt a .310 daimeter bullet be to tight of a fit for a .308 diameter barrel??? [quote]

The Mini-30 has a throat diameter that will allow the chambering of .310 bullets, with a .308 bore.