Yea i use a pellet gun to pick off squirls all the time.
what i do more than i should i but a BB in the chamber then drop 3-4 more into the barrel at the top... (Shotgun) if your withing 50 feet ton of damage! works great. But my gun is a pellet/BB gun and it is the one you can pump alot. If you put more than 4 in it will kick some and the velocity slows up real quick not a kill shot. so stick with 3-4 BB's.