The bb cap just mentioned is a nice short distance squirrel killer but they tend to be sort of hard to keep accurate. Its a .22 round ball, not a bullet shaped projectile. For a long time I have an old sears .22 single shot and fed the bb caps to squirrels and rabbits using it for years. After trying the cb caps that was all I have run thru it now.
I got that gun in 1963 and shot nothing but short hollow points in it for squirrels and rabbits while hunting. I have no idea how many pheasants hit the dinner table using it. I don't know if I ever shot a long or long rifle thru it. Been around a long while but the cb caps are still keeping critters in check along with the pellet gun.