Ground squirrels in Idaho are small and not hard to kill. Expanding bullets are desired in my experience as solids tend to go on through and not anchor the critter where he stands. Expanding ammo seems to benefit from higher velocities to help with the expansion. Ranges are long and it's often (always) windy where I live, so higher velocities are an aid to more effective shooting. I use a 221 fireball quite a bit for the longer range targets and the rimfire for closer. Maybe out to 80-100 yards for the rimfire and out to 250-300 for the centerfire. Hits are not guaranteed, at least by me.
