A 45 cal 400 grain lead FP bullet at 1200fps will shoot thru, and kill any deer standing. Isn't this pretty much the same load that killed off the Buffalo, and thousands of Grizz bears back in the good old days? Most handgun hunters consider a 300 grain, lead FP 45 cal bullet (100 grains less) out of a revolver at 1200 fps to be enough for most any large north american game at reasonable range. That said, I would use a 300 grain HP on deer - the bullet expansion might drop a lightly constructed whitetail a little quicker, with about the same low recoil as the 400 grain CB load.
Larry