I have several of the Korean 9mm MP5 mags (both generations), and my full size gun runs fine with them. No hiccups whatsoever. But when I run them in my K, I occasionally get some feeding issues. With the HK mags, it runs fine. I'm wondering, since the K has a faster cycle rate, could the problem be with the magazine spring? Has anybody had similiar issues and replaced the with HK springs and the problem been fixed?