I have aT/C factory Encore barrel in 7.62X39, it has a .308 bore. I shot a few Wolf .310 rounds in it before I knew of the difference. Hoping that I hadn't ruined the barrel, I got some brass and 125gr Sierra bullets. It is a great shooter with the 125s, as it was with the Wolfs. I must have shot just enough of the oversize rounds to break the barrel in. It is on a .308 diameter diet now and is a keeper!
FM