obviously they are different. I mention reloading because even factory loads leave very little room and even a slight bit too far on a reload can make them stop cold. The very blunt shape of the round doesn't help either. I'm seriously thinking about changing springs in my carbine mags as here in California we can't just buy more and a few are troublesome. I have been shooting carbines since Boy Scouts and that was in the mid 50s. I think that magazines are the weak link in the weapon, just my opinion.