177 at those ranges, easy peasy, with head shots, good roundnose pellet like Crosman Premiers, I'd use a light pellet in a low powered airgun to keep trajectory decent....and a heavy for more efficiency if using a stout gun.
ME, I have enjoyed the .20 cal, with 14.3 gr Premier domes.....dropped a tree squirrel about 70 yards.....they Whack stuff, so will a .22.
But again, to YOUR ranges, the .177 is fine, if you place your shots.
