I use this Ruger 10 / 22 with the optional BX Trigger installed with Simons .22 mag 4x power scope to kill Feral Hogs & Coyotes at 75 yards headshots are possible I found the CCI 40 Grain copper-plated hollow point Velocitor to be the most reliable and accurate. A shot placed 1/4 " below the ear is a kill shot with this ammunition. I have killed well over 150 Feral Hogs and over 40 coyotes with just a stock Ruger 10/22 Rifle. No need to put 2 grand in a 10/22 to make it accurate, It's accurate enough right out of the box to kill Coyotes & Feral Hogs at 50 & 75 yards. The power of the .22Lr is often underestimated it has been the caliber of choice of the professional poacher for over 100 years. It can take Gators, Razor Backs, Coyotes, Bob Cats, Mountian Lions, Deer, Fox, Coons , as well as several Varmints including the Two-Leg Varmints. Yes in my opinion the .22 LR can be used for self-defense. If a single shot of a .22 LR to the head of a Wild Boar well over 200 pounds brings him down it will bring down a Human Attacker Down as well with a shot placed to the Head Neck or Torso. I am not recommending that you USE a .22LR for self-defense I am saying it's capable to use for self-defense. I carry a .22LR Ruger LCP II lite rack as a backup Loaded with the CCI 40 grain Velocitor mentioned above to my EDC 9mm Hell Cat by Springfield Armory. A Feral Hog and a Coyote were taken with just the factory Iron Sights before adding a cheap budget scope to the Ruger 10 /22.