Well, outside of a Vulcan, I guess my doomsday gun wouldn't be a pistol at all. Heck, it's doomsday, whos gonna give me a hassle? No, my gun would be my SKS. It's not the most modern gun in the world, but they are reliable, have a better cartridge for doomsday operations than do the AR's, and in the case of my SKS carbine, are just as short and handy. In the case of my other SKS, they also have a bayonet, allowing me to poke my way through doomsday lines at the 7-11. I would likely carry a pistol as backup, and given that capacity is king with the large, unruly doomsday crowds, I would go with my PT-99. I would prefer .45, but spraying down a doomsday crowd is easier with 14 shots than it is with 7.