We recently picked up several of the newly released Magpul Gen3 40 round PMAGs. When I first picked up the mags I couldn't help but think how cool they were. Everything about them looked like a standard PMAG just stretched out. The 40 rounder has the standard waffle style pattern as any of the other PMAGs, it's just 2 more "boxes" or rows longer. I worried it may make going into the prone a little harder. Messing around in the house proning out on the floor I realized it isn't really a issue and using the mag as a monopod, the 40 is still a comfortable height for me at least. Grabbing two boxes of 5.56 I wondered if it was going to get weird when loading. Once again not a concern. If loading a M16/AR15 magazine is difficult for you, I don't know what to tell you. The big PMAG loaded the same as any other PMAG and didn't seem to take any extra force, it just took more bullets. The PMAG40 locked home in all 4 lowers I tried it in even with the mag completely full and bolt foward. The new PMAG has a tab on the back side of the mag along the rear spin to keep from over-inserting the mag and seems a little thinner than older generation PMAGs. There was however a little more wiggle front to back in the mag well with all the lowers, but not much. I loaded all 5 of the PMAG 40s and tossed them in the range bag.
The next day me and the SMC Tactical NC crew headed to a USPSA carbine match at a local range. All of the guys had me buy them a few and we were all going to use them and see how they worked. As to be expected for a PMAG or pretty much any Magpul product they preform amazingly. The match was 5 stages and none of the stages required a reload (one did require a load however) and none of us had to do any. While 40 rounds is only 10 more than a standard magazine, 10 rounds can go a long ways. Some of the other competitors had to make reloads to make up shots while we just kept blasting. I used each of the mags for a different stage and all did the same, as did the other guys, they just worked.
I own one of the Surefire 60 round magazines and unlike the rest of their products I have used for years it does not work. The Surefire chokes after the first 20ish rounds with the rest of the remaining rounds failing to feed. I called Surefire and they were very pleasant to deal with. I will be mailing it back for a repair/replacement. Until I get the chance to test the next one or repaired mag out, it will be taking back seat to the PMAG 40. The only "downside" to the big PMAG is they do stick out of mag pouches pretty high, but once again, not much of a issue really.
Video from the match and of the team here!