Must use hv ammo,rem thunderbolt or Winchester super x works great.I did not strip mine down and clean it right out of the box but it did clean the barrel.using the mag loader works best if you push mag loader all the way down then release just enough pressure off to slide cartridge under.cartridges should slide in with no force.If you force them they do not line up correctly.I have 400 rnds Winchester super x and 300 rds rem thunder bolt with maybe 2 fte '3 FTf.I think I like the Winchester better