I have a similar problem with my Keltec P11 mag, which is similar to or the same as a S&W 59 series mag. Mine is a 10 round mag (9mm of course). Any amount over 7 rounds in the mag and it rattles, regardless of weather it is in the gun or not. My particular mag is a Mecgar brand.
I've been meaning to start a thread about this for quite a while and just never remembered to do so. I was wondering if anyone else had similar experiences, with this brand or any other brand of mag?
The two enemies of the people are criminals and government, so let us tie the second down with the chains of the Constitution so the second will not become the legalized version of the first. - Thomas Jefferson