I think they are the best magazines available hands down.
I've heard the .204 Ruger rounds won't feed from Pmags
When I get my Pmags, I will have to give this a try. But, I really do not see why 204 Ruger would not feed from a Pmag if it feeds from a standard mag.
Supposedly it is their follower, so possibly a metal mag with a Magpul follower won't run .204 reliably either.
opinions on magpul pmags
If the military has banned them, someone forgot to tell CENTCOM. They are issuing them in Afghanistan.
I have a bunch of the Pmags, and they work great in the guns they fit.
I have two Armalites that will not take them. They are all either very tight to insert, or wont go into the mag at all. These same guns have no issues with the GI and Colt mags Ive used all along until I got the Pmags.
I've seen them fail on others and have had them fail on me in many occasions.