If you are interested in the weapon & gear scene you've probably heard of MAGPUL.
http://www.magpul.com/
MAGPUL is an innovating company which produces accessories for weapons like slings, sights, handguards, stocks, ... They even designed their own weapon system, the MASADA.
One of their most popular items is the Pmag. Made from an impact and crush resistant polymer construction, it was first announced in early 2007. The Pmag is a 30-round 5.56 NATO Polymer MAGazine for AR15/M16 platform weapons. With millions fielded to military, law enforcement, and commercial users, PMAGs have become the de facto standard for magazine reliability and durability. Since 2007 the Pmag underwent a lot of modification to be compatible with other weapon systems than the AR family. Since some time MAGPUL has Pmag M version which is fully compatible with our FN FNC. (theversion marking is visible on the bottom plate of the mag)
I have tried some Pmags and must say they feel light and platic like, because they are ;-) But after shooting a couple of mags I wasimpressed.
They claim to be stoppage free compared to the Stanag metal magazines. I checked both mags and must say that the follower is much smoother on the Pmag and doesn't tilt when pushed on one end.
Neverthless, the goldon rule still stands: Only put 28 rounds in a 30 round magazine.
Even the Pmag tend to jam the FNC when fully loaded.
I've been using them for over a year now and have had no issues what so ever. They come in a variaty of versions and colours and have their own accesories like a dust cap (included) and magpuls.
From left to right, Stanag metal mag, standard Pmag, Pmag with maglevel.
Once again, they are tough ;-)