What year did you purchase your C15, and what does the feed ramp look like, and what is the feed ramp made out of? I just purchased a brand new Bushy C15. I have heard of these problems in the past, but have been told they are fixed. I have only put 2 full 30 round mags of ammo through it so far, but had NO problems. One mag was an OKay ind. mag (w/ green follower) and the other mag was the nice Bushy mag that came w/ the gun(also a green follower) I used the same ammo each time. It was cheap "Ultramax" ammo I bought in bulk on the internet, and had not one problem so far.
I was wanting a description of your feedramp, so we might compare to see if there is a design differenc, or if I might start to see these problems at some point in the future.