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KRISS USA Mag Ex2 40-Round Glock Magazine Review


In the world of increased capacity, pistol-caliber magazines the MAG Ex2 stands alone. Not simply because of its capacity; several SMG magazines have matched it. But because of its combination of increased capacity, reliability and ingenious durable design.

For the uninitiated, the KRISS USA Mag Ex2, is a kit for standard capacity 9mm Glock magazines. It was developed by KRISS USA for use in their ultra-high ROF Vector sub gun. 

KRISS Mag Ex2 9mm 01
Increasing the standard 17-round magazine to a staggering 40-rounds, the KRISS Mag Ex2 is in a league of its own.

Two of the biggest issues with the 33-round extended magazine originally designed for the Glock 18 machine pistol, are reliability, and bulk. Because the 33-round magazine relies on the original form of the Glock magazine, it becomes comically over-sized and more than doubles the pistol’s overall height.

The engineers at KRISS USA solved this by replacing the monolithic magazine design with a two-piece conversion kit. Basically, the Mag Ex2 consists of a sleeve a new base plate and extended magazine spring.

The original magazine slides inside the sleeve, with its base plate lips securing the sleave to the original mag body. 

Here is everything included in the Mag Ex2 kit: a two-piece sleeve and the extended magazine sleeve.

While this might not seem as secure as a one-piece magazine, my experience has proven just the opposite. I’ve had both Korean, and Glock-brand 33-round 9mm magazines catastrophically fail on me in the past after only a few hard reloads. Thus far, I’ve tried to destroy these magazines by loading them as hard as I can, and dropping them on concrete from shoulder height without any success.  And given that 40 rounds of 9mm (at 0.4oz per 115gr round) adds an extra pound to the magazine’s weight. Meaning it hits the ground with vastly more force than when empty.

KRISS USA Mag Ex2 Glock 19x
The authoer's personal Glock 19x with all the fixings. The Osprey 45 from SilencerShop, a Streamlight TLR-8A Flex and of course, the KRISS Mag Ex2 9mm. It looks very appropriate on top of the, "no trespassing" sign.

But what about the other big drawback of these magazines, reliability? Admittedly, I’ve only put around 500 rounds through the magazines thus far.

However, in that time I only have a single issue with one of the magazines when sand and oil were introduced to the internal components. The added sand-oil sludge caused the rounds to bind inside and stop feeding to the gun. The issue was resolved by striking it firmly in my palm to seat the rounds at the back of the magazine. After this issue, no other malfunctions were encountered.  And in all fairness, basically any magazine will bind if a thick substance is introduced that adds substantial friction.

KRISS USA Mag Ex2 Kel-Tec Sb2k
The Mag Ex2 works in any firearm designed to feed from 9mm Glock mags, like this Kel-Tech Sub2k Gen 2.

Overall, the Kriss Mag Ex2 is a home run not just for KRISS, but also shooters with a need for added Glock capacity. It might not be the cheapest option around, but cheap and reliable don’t normally go hand and hand. So if a shooter is looking for increased magazine capacity on a firearm that could see serious use, the KRISS Mag Ex2 is a sure thing. For more information, visit  www.kriss-usa.com.

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