I hunt squirrels I think forever I can remember. The past few seasons I have been using my Mossberg 835 Ulti Mag 12 guage pump shotgun, with a 28 inch barrel. I am shooting 2 3/4 inch shells out of it, hi power #4's. I have my full choke screwed in it right now, with all the leaves and also my shots are good piece a way sometimes. Everyone ask me why such a heavy load for squirrels. One thing I dont like a cripple, and second it gets out there and reaches for them long shots that other people say you cant make with a shotgun and drops them dead on arrival. Before I got my Mossberg, I have hunted with my Winchester automatic 12 guage, using the same loads with the same effect. I switched to the Mossberg when I started turkey hunting. It came with 4 different chokes, so it is now my all around gun. Any way that what I shoot them with, and another thing, it dont messed them up to bad at all.
Swampchopper