Revolver,stainless steel,4" to 6" barrel in either .41 Remington Magnum or the venerable .44 Magnum.
I prefer the .41 myself, it offers a bit flatter trajectory with the same, or close to the same energy as the .44.
You might consider one of those new x frame smith and wessons in the 500 caliber.
We have sold several of these and the feedback has been favorable, but boy oh boy those things do pack a wallop.... on both ends.
Keep in mind... even if says "magnum" but your shooting it out of a short barrel, your not creating any more energy than a much lesser cartridge... you just get a huge fireball and horrendous bang! So if you dont want to carry at least a 4" barrel with the two above mentioned rounds and at least a 6" barrel with the 500, than go with a .45 acp or 10 mm auto loader.