I have had mine for 2 years now and probably put 10,000 rounds thru it and as far as I can remember it didn't like one kind of ammo that had a waxy film on the bullets. I can't remember which .22 ammo it was but right now I am sticking to American Eagle and it will shoot a 3" gong everytime at 25 yards and have taken many gophers with it. Great little plinker for the kids to play with. I had my 13 year old daughter and 16 year old son with me on Saturday to the range and they shot a whole brick of ammo, 10 boxes without one FTF or FTE.