I always used a 12 gauge on squirrels unless all I had with me was my .22 pistol. Use a smaller shot, and you'll do fine. The circuit judge is an interesting gun, but really a toy. If you got really close, it would probably work. From what I've read, the smaller the shot size, the more prone to the doughnut pattern they are. 12 gauge and 20 gauge are much cheaper for the small game loads, and the slugs pack much more punch for deer. If you do decide on the circuit judge or judge pistol, be forewarned that in NM, shotgun is only a weapon that is designed to be fired from the shoulder (for the purposes of hunting.) That means I cannot use my pistol gripped shotgun under state law for hunting squirrels. At least, that's how I interpret the law. You'd have to do a lot of product testing with that gun to see what shells pattern acceptably and at what range.