There are a few different types of squirrel hunting, each of which may require a different type or size of gun. For example, if you're planning on still-hunting squirrels (walking around and looking for them), you might want to use a larger caliber rifle like a .22 so that you can take them down from a distance. If you're going to be stalking them or setting up ambush sites, then you might want to consider using a smaller caliber gun like a 20 gauge shotgun. The smaller pellets will make it easier to hit your target, and the reduced recoil will help keep you accurate.