Shot loads work well in a single shot pistol but revolvers are troublesome. As "goodshot" mentioned, recoil of one shot may well dump the load in other chambers. And revolvers have a limited capacity. There just isn't much room in the chamber for powder wads and shot. Black powder is a low power, high bulk propellant and to get reasonable velocity you must fill more than half the chamber with powder, which doesn't leave much room for wads and shot. No doubt a .44 could be effective with shot at a few feet but you'll never match the commercial shot loads in centerfire revolvers and even those are of questionable value.
