I am sure a 44 or 45 RB or whatever you want to call it will kill a deer, but I wouldn't want to try and track it through our woods.
I've hit them with a 54-Maxi and not have them bleed a drop externally. One time in particular, the only reason I knew it was a hit was because the deer went down at the strike, jumped up and ran 100yds or so, through the thickest stuff this side of Seattle. I never found a drop of blood.