I've logged a lot of miles with a .22 rimfire as well as .45 colt, .38 special, 44 special and .357 magnum. ...and a few with a 9 and 10mm and .45 auto. Every one was a comfort. Most useful are probably the .22s and a .357mag. A cylinder full of magnums for bear country and a pocketful of .38 spls for potting a rabbit covers things pretty well but you can carry 100 rounds of .22lr with greater ease and be be set for most of what a pistol really gets used for. Armed beats unarmed and a .22 in the hand makes bumps in the night less worrisome...but I tend toward centerfires for trail companions these days.