I would never use a small cartridge, that is, smaller than a .243, like timbercruiser said. I know one girl who killed 3 deer with a .223 Rem, and the shot placement was good (the range was less than 50 yards), but I still believe in Human Error. Not worth the chance. I'm not saying that a less accurate shot won't kill it, but that if the deer does run anywhere close to 100 yards, recovery could be difficult since the blood trail could potentially be smaller.