Considering most self defensive confrontations are at under 20 yards and fewer than 4 shots are fired,
according to FBI data, I always thought that the 3.5" barrel 500 revolver,
with reduced velocity loads, lets say a 320-350 grain semi wad-cutter
at about 900 fps would be a rather interesting self defensive tool.
too large and heavy to be practical,
but it should darn sure get an aggressors attention,
and change is anti social intentions,if it hits center mass,
without posing excessive penetration or recoil,
for an experienced, large bore magnum, pistol shot, that puts it in the same energy level,
as many 10mm loads but with a much larger diameter and heavier projectile moving slower.