Started with metal mags and built to Bushy specs with a change in spings and non tilt followers. No longer use or buy metalic mags, but use P Mags exclusively. Heavy tested by an outside source, they out last wear, drop, mud, sand, or whatever you throw at them including temperatures and being run over by a truck. Metal fail quickly in many of the tests, all fail with repeat extreames. P Mags are my choice, and I use both the plain and windowed.