It depends if you want to bring home a lot of squirrels or just want to plink at them for a while. A shotgun will get you a lot more squirrels in the end. Squirrels are really easy to miss with a .22, but it's a lot of fun. If you're using a shotgun forget the .410, use at least a 20 gauge with high brass 6 shot (full choke), drop that to 4 shot if you're using a modified choke. Nothing wrong with a 12 gauge on squirrels either.