PROMAG S&W M&P9 9MM 50RD DRUM BLACK - 9mm Caliber, OEM Origin

Profile appears to be similar to current mags for the S&W FPC, holes for catch are bigger, the mag doesn't come close to staying in the firearm. Otherwise, construction seems to be good. Follower is sketch but I didn't even try loading as there was no point.

Unfortunately this promag 50 round drum magazine does NOT work with my M&P9 M2.0 full size or my M&P FPC. It will not stay locked into either gun. It does engage the magazine retainer/release but has excessive loose fitment which causes the magazine to just fall out if you shake the gun or twist the magazine. I found the problem to be caused by the width of the promag on its forward side where the retainer/release engages. It tapers down to be 1/8" narrower than the factory magazines. If promag would make it the same width as the factory magazines it would work just fine. Seems to be a quality made product aside from that.

I just use this in the backyard range, I was a little disappointed in the struggle to load and each time it is inserted into the firearm, the mag has to turned to relieve tension from the spring to seat properly.