What would that caliber be? Mine would be 44 magnum. You can put it in a rifle and/or pistol. In a survival situation it could gather meat, defend your camp/home and can be shot by anybody in the family. I think 22lr is a good survival rifle. The reason I wouldnt choose it is because I can make good bows out of different woods, use a slingshot effectively and can build traps/snares, throw knives, tomahawks, chisels, long nails and other stuff. With those I can (done it before..) kill small game silently. The other down side to a 22lr is it is not a preferred SD caliber. If its an "end of the world" situation and you have to defend your camp/home its good to have a caliber that can take someone down without an absolute precision shot. The 44 magnum can cover basically all types of survival situations. So, whats your survival caliber and why? God bless.