You know I have been thinking it might be the magazine as well. Because I use them for duty I keep the mags loaded and on my belt/in the gun. I have however compared them to spare mags I keep unloaded and they seem to be the same width at the top opening. I also pulled the mags apart and left the springs out for a few days and when I put them back together I have left them unloaded to try to releave some of the tension on the spring.