i know that the 6x ACOG calibrated for 7.62's BDC reticle is based on 147gr. 7.62 NATO ball ammo. my two question is; what barrel length are the nato published velocities from? second, if im considering buliding a 16" .308 (higher pressure as most know) to shoot moly'd 15gr x bullets (actually the lazeronis come that way but essentially the same thing), how much variation would i get from the bdc hold points? would it even be worth it to go with the acog? thanx for all info.