223/5.56, 7.62x39, 5.45x39,6.8spc, 6.5G, 30 carbine, are common swaps for the AR-15 and they all use the standard ar-m16 uppers and lowers. for hunting deer the 6.8/6.5 and 7.62x39 would be the best bets in the AR-15 sized frames.--
i have been very tempted to do a 6.8SPC because i have been running a 6.8spc2 bolt for my 5.45x39 wilson barreled upper for several years. all i would need is a barrel and a mag to run some 6.8-- if i was so inclined.
bigger stuff like 308/260/243 will need the bigger AR-10 sized platforms.