If you can't bring one down with a .22 its due to bad shot placement. .22s are all I use and out of a couple hundred I've killed I think about 5 have taken a second shot to bring down. Most are taken at 70 yards or under with cheap bulk wal-mart ammo. Just remember; think, aim, shoot. Good spot is the artery that runs down the neck; you can see the ridge if you have good eyes, lots of artery, nerves, and sometimes mashes the throat with it. (who knew taking an anatomy class would help me hunt)