Interesting item of note to my fellow gunnies out there. As most of ya'll probably know, one of the fastest growing up and coming "black rifle" companies is Magpul. Magpul started out making an attachment you could place on the base of your AR mags to make them easier to draw out of your mag pouches. From there they've branched out to all sorts of cool accessories, including the Magpul Masada, which was bought out by Bushmaster as a 21st century combat rifle.
Their Pmags have been all the rage this year. I know a lot of folks of the tactical mindset, guys that get paid to get shot at (and shoot back) and they've told me nothing but good stuff about these mags.
So over the past few months I purchased 8 of them. Ran one through my Bushmaster, and it worked just fine. Kept the others tucked away for a rainy day until I tried running the one mag through a DPMS rifle. While the mag seated fine, it wouldn't drop free. Tried the mag out in an Olympic Arms rifle. No go. Not only would it not drop free, I couldn't even get the mag to seat properly.
Got me thinkin'.... So I took out the other mags and discovered the following:
The Bushy liked every one of them; each of them loaded properly, dropped free and locked the bolt back on an empty mag.
The DPMS was hit or miss. Coupla of the mags worked fine, but the rest would not.
The Oly was even worse. I couldn't get any of the mags to seat without beating the snot out of them - and who wants that??
So, word to the wise. If you bought a bunch of the Pmags this year, and stashed 'em, check to make sure they function 100% in your rifle(s).