Let me preface this by stating the issue is with the Daewoo DR-200 which I'm sure Magpul was not designing for. That being said, all of the other AR15/M16 mags tested worked in the Daewoo.
I noticed last time when I took the DR-200 out, the bolt catch was not activating after the last round out of the PMags. Decided to take a closer look today and found that there was not enough material on the follower to activate it.
I guess since they are designed to be fully seated in an AR15 magwell, this isn't an issue but since the Daewoo's have shorter magwells, the magazine has some front/back movement. When you are not putting an pressure on the mag, the bolt catch will slip onto the rear of the follower rather than catch on top.
Wondering if anyone else out there can confirm this.
Why would the PMag design have a shorter follower?
Here are some pics.
HK, D&H with Green Follower, PMag with window, USGI Center with Magpul Follower
Pic showing the front/back movement of a mag when inserted: