I've had no problems with squirrels using a .22 hammerli 850, .22 MaximaThor, and .25 MRod. With the MRod , I use PolyMags, JSB 25.39s, or JSB MK IIs 33.95. Head or mediastinum shots work well , they never move far, if at all. With the Hammerli 850, Sniper lights, and Metal mags work very well. I only had to chase (walk after ) one with the hammerli, and wack him with a stick. I used a Fallcon 13.something on this one. These are very accurate with this rifle. The .22 Maximathor loves H & N Barracuda Match 21. somethings. Head shots and mediastinum work well. Accurate shot placement is the key to a humane kill. Right through the eye, or on a lateral head shot, between the eye and ear. A neck shot, at the base of the skull, aiming for cervical vertebrae #2 disrupts the spinal cord and mid brain. A good technique from behind, or the side. PolyMags work very well for this.