I was taught long ago to never fire a rifle unless I knew where the bullet would land beyond my target, and I've applied that same rule to my squirrel hunting. So, no, I don't shoot squirrels in the open treetops with my 22. As others have said, I will shoot them if my bullet will land in the trunk or a solid branch. Sometimes you have to wait patiently for them to move to a favorable spot. Adherence to this rule is why I use a shotgun in the early squirrel season, when they're mostly in the open treetops. But this time of year (winter) they're often on the ground, so I get to hunt with the preferred 22, and I don't have to worry about biting into shot. For treetop shooting, I've decided 28 ga is best for me. 3/4 oz of #6 will drop 'em, but won't fill 'em up too bad with pellets. I no longer have a 28 ga barrel, but I bought an adapter just so I could shoot 28 shells from my 20 ga barrel.