hate to sound obvious and redundant, but... ruger 10 22!
mine has taken more squirrels than i can count, and a few rabbits; and i love it! Butler creek steel lip mags are the 25 rnd mags to get, and I would suggest some sort of optic. Right now mine boasts a simmons 3-9 x 50 scope. It is very compact (i have the carbine model) and that helps when fighting through swamps to get to the untouched squirrels' nests that it is so good at "eradicating"! it feeds copper plated rounds better, but if you're careful, regular non plated rounds work just fine. Though I haven't tried, a scope, 25 rnd mag, and cci stingers would make a great long range anti- prairie dog or gopher gun! (NW Florida doesn't have much for a 22 besides squirrels, possums, snakes, and rabbits!)