First, Thanks in advance for any help. Alright, I have two calibers in mind, the Alexander Arms rounds. The 50 Beo and the 6.5 Grendel. -The 6.5 is cheaper to shoot (Wolf). Its adequate for mid sized game, (I would use it up to the biggest Mule deer out there, and anything under). Great BC, better than the 5.56 or 7.62 NATOs. Great long range cartridge. -The Beo is a 50 cal, I mean come on, thats awesome. Its enough for any North American game, and I love that too. I go elk hunting so this really helps. 300-400 grain projectiles, . It would blow a hole in anything you want. After 200 yards it starts to drop like a rock. But thats not a big problem with me, so. -The thing is I want a larger cal AR upper. But I have a .300 Win Mag, .308 Saiga, .30-06, 7.62x54, .30-30, and 8mm Mauser for elk/deer/bear. So if you can, HELP, and again thank you.