Just a quick question. In bulk, wolf ammo is .20 a shot (for the 500 round case). Everything else 5.56/.223 is around .35-/45 a shot. So, I figure I can save myself some money by shooting a 7.62x39 round, without going with a com bloc weapon. How much does a new 7.62x39mm upper for an AR15 cost? No bells and whistles on it (HBAR, MOLY, chrome lined, etc are not needed). Whats a good twist rate to look for in the barrel, if there is a desirable one? Will it go right onto a lower thats for 5.56x45mm/.223 Remington? If y'all include a link for future research, it'd be much appreciated.