I've been sitting on a Rock River lower for maybe twenty years. Looks like if it is ever going to be turned into a rifle I'd better get on with before Biden makes it impossible. I don't know what I don't know, so I seek advice as to who's barreled upper to use. Something in a flat top, reasonably accurate that will feed 150-160 grain lead bullets from a ten round mag. I have had good luck using 1 in 9.5 with the 7.62 X 39 so would like to stay close to that.
Is .308" the norm in a deal like this or is .313-.3135" used (like the SKS and maybe AK) to accommodate mil spec?