I realize it all boils down to your ability to make shot placement, but I wondered if a 4" barrel is adequate for deer hunting?
As many have noted, the length of the barrel doesn't matter in and of itself, given the ability to put a bullet of sufficient power in the right spot.
I've killed whitetail with a DAO 3 inch S&W Model 696 44 special, shooting 240 hardcast LSWC over 14.n(trying to remember, might be 14 or 14.8...getting old) grains of 2400. That bullet is probably going 1000 FPS (I can't recall). Through-and-through the chest. Deer usually run a bit and lay down to die.