i use full choke 12 gauge with #6 shot. i dont understand what they are talking about. i can always get all the shot out of the squirrels pretty easy. I also use a .17 hmr but i wouldnt recomend it for squirrel because if you dont make a good head shot it is catastrophic on the meat. Id try a .17 mach 2. i dont think it would do a lot of harm to the meat