For those wanting to hunt med size game to eat, then sticking with well designed non-fragmenting projectiles (typically bonded or monolithic) is best.
In .223/5.56 mm for hunting deer and hogs under 200-300, go with bullets like the Fed TBBC, Speer Gold Dot (or identical Fed Fusion), Nosler/Win Bonded, Nosler Partition, Rem CLUB, Swift Scirocco, Barnes TSX/TTSX, and Hornady GMX.
6.8 mm is great for deer and hogs out to 300 or so, again using bonded or monolithic projectiles.
6.5G works for going longer using an AR15, with the limitations discussed by SLG.
For larger game like elk, I prefer a .260 Rem/6.5C, .308, .30-06.
In a bolt gun, I find no reason to go with .223. .300 BLK, 6.8, 6.5G and stick with calibers with more case capacity like .260 Rem/6.5C, .308, .30-06.