I prefer to have a neighbor trap out muskrats and beaver, but I have killed a few beaver and a lot of rats with a 22LR through the head while they are swimming. With a 22LR, you need to know what's down range because they can skip if you miss. I am quite a bit more successful using a rest compared with freehand. I was not naturaly a good shot, but I practiced and got some coaching from a competitive shooter. There are a number of techniques that can improve accuracy.
