Originally Posted by
Army Chief
If there is any bona fide argument against having both old and new (Rev M) PMAGs, it would probably have less to do with any functional shortcomings and more to do with parts commonality issues, since the internals from one generation are not readily compatible with the next.
If you try to put the spring/follower from a Rev M mag into the older bodies, or vice versa (I can't remember exactly which combination is more problematic), you are going to end up with some malfunctioning mags in which the follower won't travel all of the way up to the feed lips, leaving a gap that won't push the final 4-5 rounds into battery.
In the end, so long as you aren't mixing and matching old and new parts, I see no issue with having a nice stockpile of both types.
AC