I use SK Standard almost exclusively and can not remember a squirrel that got away or made it back to the hole if the shot was placed close behind the shoulder or head shot. If hit in the gut, then yes, they tend to require a second shot. I prefer head shots to all others. I did find a supply of Eley Sub sonic HP's that were being closed out and picked up 2k. After a couple of trips, they are being used for varmint control only or head shots only. Even at sub sonic, the damage if they hit the shoulder is unacceptable in my opinion.
I do take a 16ga on occasion to shoot squirrels, but it is a rarity.
