I shoot CCIs now and never a problem. I think they have a little more power in them to cycle the action, but not sure.
CCI are great rounds and I like them in my rifle, though if I try to shoot them in my pistol they will jam everytime. I don't know if it is because they are loaded a little hotter and the case expands or what but everytime I try to shoot them in the pistol they will fire but not eject. I have to dig out the spent case.