The fist thing i look at is the crown, to see if there is anything that would be suspect in performance. Next is the throat to see if the rifling is all in-tick and nice and squire. than the bore itself, if possible ask to have a perspective rifle swabbed for a better over all look. After all its your 100.00 bucks. I stay away from counter bored nagants, that's just my preference. Things that i look out for is egg shaped crowns, worn out throats with no clear definition and just plain crappy bores. All and all my nagants shot 2.5Mao at 100yards w/ reloads. If you reload slug you barrel.......mosin can be anywhere from 308 to 313. I hope this helps anyone picking out a rifle!