Having ammo on hand is one issue...proposing that #4 Buck will penetrate as well as .22lr is another. It won't. CCI Stingers, for example, are smaller caliber, yet carry 133% more energy than a #4 Buck pellet. That being said, why are you comparing Buckshot to .22lr? When it comes to external and terminal ballistics for stopping humans, why would .22lr be any standard of comparison?Why I would not use it (now) is because I don't have any. Lots of 00 and #4 but no #1 or even 0 buck. Never said that there may be better loads (I previously agreed that #1 was really impressive and that I never gave it much thought).
Just saying that #4 at living room range will drop someone just as well as a 22 if the shot is placed where it needs to go.