No, I wouldn' t dare use a .177 air rifle on sqrls, are you kidding, at least a .30-06, if not a .375H&H!!!
[&:] Really though, as long as you can' t see your bb in flight (or you have a 10pumper), you' re more than " enough gunned" . Take some fishing line or dental floss, get them up a tree (if they don' t go in a hole, tie the floss to a sapling, and step to the other side of the tree they' re in from it, then shake the heck out of it, they' ll bounce to your side, and hit them in the head with a pointed pellet. If you' ve got some rat terriers or jack russels, take them, the sqrls will sit up there and worry so much about the dogs they won' t even glance at you while you swing around and harvest them.