I’ve been sitting on this Sig Sauer MPX K review for a long time- over two years! I first had it at the range in March of 2019. That’s the same March of 2019 that the COVID-19 pandemic took hold where I live and had the immediate effect of shuttering nearly everything and this post was put on the back burner. I apologize for the lateness, but sometimes pandemics get in the way.
Back in 1995 I was a 19 year-old that was new to guns and gun collecting. A young Marine making next to nothing, I saved what I could to buy the guns I wanted. I believe at this point in my life, I had owned a Mini-14 in Choate stock, a Colt AR-15 SP1, and maybe a K1A1 (I’m unsure of the chronology). One day I was talking to one of the senior guys in my unit and he offered to sell me a 9mm HK rifle- that rifle turned out to be an HK94. I literally spent my life savings (until that point in time) to buy it. It was a short lived purchase and I’m unsure why I sold it. It was as close as you could get to an MP5 (one of the cooler guns around in the mid-90s, and some would argue still is today), sure the long thin barrel looked a little dopey, but hey, it was as good as it got.
While the MP5 was always a bit of an icon, other platforms never really challenged it until Sig Sauer introduced the MPX. The MPX, available in rifle, pistol and military configurations looks a lot like a grown up MP5. The controls are similar to a scaled down AR-15, improving ergonomics and adding features like a last round hold open (only present on the 40 and 10mm MP5s) available in a MP5ish platform.
The test gun shown here is an MPX K pistol. It has a folding arm brace, that at the time of production and this writing, classified it as a pistol in the United States despite some discussion by the ATF as to whether or not the brace would in fact make it an SBR (short barreled rifle) and subject to additional regulation.
To Sig Sauer’s credit, the controls of the MPX are very similar to those an an AR-15/M16 M4 type rifle. This means that for many end users who are presumably already trained on that platform, the transition to the MPX is an easy one. Unlike the MP5 it has an easier to manipulate safety, easier to use magazine release and a last round hold open (note the short ambidextrous safety lever in image above). The MPX feeds from a 30-round polymer double stack magazine.
In addition to the traditional AR style controls, the MPX is ambidextrous from the factory. Unlike an AR that requires special upgrades, the MPX is ready to go right out of the box.
Takedown on the MPX is familiar to any shooter with experience on the AR platform. The take down pins are remarkably similar and while it has a captured recoil spring assembly that is unique to this system, the rest is fairly straightforward.
This model of the MPX, the MPX-K has a folding arm brace. The mechanism for this folding brace is very impressive, with a solid, sturdy feel.
This MPX didn’t include a sight system, so I equipped with with an EOTECH.
Firing the MPX was a real pleasure (that is my buddy holding it for a photo). It is nice and compact with a soft recoil impulse. During my initial rounds of testing, the AR type controls made for an easy transition to the new platform.
Prior to shooting a series of qualification courses with the MPX, I ran a bunch of five-circle drills at seven yards to familiarize myself with the platform. I had decent split times for a new platform, .80 seconds for one round from low ready, 1.43 seconds for two rounds from low ready, 2.76 seconds for 1 one on one target, two on the second, and one on the first from low ready, and 6.62 seconds for fire two, reload, fire two on the same target. I’m not sure I’d be able to match these times with an MP5 that started on safe unless I changed the safety around or started in a slightly different position.
I did have once failure to feed. This was with some fairly sketchy ball ammo, so I’m not blaming the gun but I wouldn’t have felt right if I didn’t include it.
Overall I’m pretty impressed with the MPX. I still remember how impressed I was with it back at SHOT SHOW 2013 when I first heard about it. It lives up to my expectations. In many ways, it is the compact 9mm that the MP5 should have been. The controls are common with the AR-15/M16 M4 platform, it is made in America and it functions very well.