Gear Review: Magpul PMAG 40 Gen M3


I know what you’re thinking. “Why would Magpul come out with a 40 round magazine?” It doesn’t make a whole lot of sense to make such a fuss over 10 extra rounds.  And while it may seem like nothing more than a gigantic middle finger to “high capacity” magazine banners, in reality this PMAG 40 is something that competition shooters have been lusting after for years . . .

3-gun shooting involves firing magazine-fed carbines very, very fast. And when it comes to carbines, 30 rounds is the standard magazine capacity. Whether you’re shooting an AR-15, a SCAR or some AK variant, chances are the standard magazine that comes with your gun holds no more than 30 rounds.


That standard limit of 30 rounds is something that match directors count on when they design their stages. If every competitor has a maximum of 30 rounds, then by requiring them to shoot 32 rounds they can force people to perform a reload before moving on. This adds precious seconds to their time, and introduces something else that can go wrong in the middle of a stage. In short, it sucks and the pro shooters do everything in their power to avoid having to reload.


The most obvious way  to increase your magazine capacity was to add a “coupler” to the magazine. A number of companies make devices that take 30-round Magpul magazines and turn them into 48-round monstrosities. But these couplers add a failure point to the magazine in the form of additional stress on the body of the mag, meaning that they have a tendency to break. Hence the electrical tape on Kay Miculek’s magazine, above.


The other option is Surefire’s 60- or 100-round magazines, which are what the FNH USA team usually uses. This gives you a nice buffer, as you now have double the rounds of a standard magazine, but they have a tendency to jam at the most inopportune moments. My Surefire 60-round magazine runs like a dream 90% of the time, but when it gets dirty things start going terribly wrong.

So, obviously, the best thing to do for competition shooters is to provide a magazine that holds over 30 rounds in a double stack configuration without any couplers or duct tape involved. And that’s exactly what Magpul has done.


The PMAG 40 looks and feels exactly like a regular 30 round PMAG, but a little longer. The only real difference between the two is that the spring’s baseplate on the 40 round magazine says “40 ROUND” on the bottom, supposedly to keep you from putting the wrong spring in the wrong magazine if you have a couple of them disassembled in front of you at the same time. It’s a nice touch, and shows that someone at Magpul was thinking through all the failure modes and making sure that the magazines were idiot proof.


In terms of how the magazines run, I put the mag through its paces in every caliber and firearm I could find. AR-15? SCAR-16S? Tavor SAR (yep, I bought one)? Works in all three, both fully loaded and when only a couple rounds are left. I even tried it with 300 AAC Blackout ammo and it ran like a dream.


What we have here is a magazine that makes all of a competition shooter’s dreams come true. It gives you enough rounds to skip the usual reloads, which should make you just that little bit faster in competitions. But it does come at a price, namely that the thing is massive. If you thought getting a gun with a regular magazine into a dump barrel was tough, this is going to be “round peg in square hole” territory. Nevertheless, when you absolutely positively need those 10 more rounds, accept no substitutes.

Specifications: Magpul PMAG 40 M3

MSRP: $19.95

Ratings (out of five)

Feel & Function * * * * *
They’re nice and grippy, and they work in my rifles. All of them.

Overall Rating * * * * *
Exactly what competition shooters have been wanting Magpul to make for years.