Seems to be ammo type that can jam them up, I tried this with 4 brand new BC Steel Lips last year and about 4-5 different types of ammo. Round nose, hollow point etc. The best and I always say this was CCI. Clean the lips after use and once in awhile the mag itself in boiling water with dishsoap, appearently simple green works well. Be sure to rinse well with more boiling water and this will help it dry faster, and blow it out with compressed air, personally I leave mine in the sun for a bit and that seems to work well.