I have several firearms in my kit, both short and long, because they add a amount of mental comfort to me. I feel best to have and not want, than want and not have. Saying that, my BOB is a BOY (Bug Out GMC Yukon). Due to injuries, I CAN NOT effectively run, and therefore can't employ the "feet don't fail me now" approach. If all else fails and I am attacked by 4 or 2 legged creatures, I've little choice but to stand and fight.
My long gun is either a .22/20ga or a .22/.410 Savage 24 combo. Being on th e East Coast, either cartridge will work well for hunting, and not much will argue with a 20ga Slug.