I shoot plenty of beavers with my 22 just don't skimp on the bullets. Use CCI STINGER hollow point bullets. Cost 5 dollars a box in canada but they really destroy a beavers skull and leave a smal entry hole. What i like to do sometimes is chop and kick a hole in a beaver dam and then sit and ambush the beavers when they come to repair the dam later that night. I have seen beavers sink before or go down and clamp onto something and die, but if the critter is hit in the head it will be floating deader than a door nail.