I'm still testing and getting the feel of the gun, but here are my preliminary results. It groups the JSB Monster pellets on medium and high power equally well and the JSB 15.89's on low power. I was hoping for good results with the JSB 18.13 on low power but at the present settings they aren't grouping well. Even the lowly Crosman pellets grouped pretty well on low power, but with occasional flyers so I rated them good minus.