SIG Sauer MPX-K Setup and Review

Posted by Kevin Estela on Aug 5th 2022

If you happen to catch me at a survival course I’m teaching, I will often make reference to self-defense options since a major survival priority is security. I will often bring up the importance of having a good pistol on you as well as rifles and shotguns in your survival firearms collection. I also talk about the concept of “better weapon, better position” that I learned from my Sayoc Kali instructor, Tom Kier. There’s always going to be room for improvement from where you are and what you have. A better option than your pistol is the rifle you should be working yourself back to. The SIG MPX-K is a firearm that hides in the gray area between concealed carry pistols and compact rifle-caliber carbines. It is a great firearm on many levels but there is a compromise. Unlike the politicians of today who say “compromise” but don’t intend to give anything back in return, the trade-off comes with actual benefits but at a cost. The MPX-K is definitely a better option than your pistol and it even has some benefits over your rifle. I’ve been a shooter for a long time and have trained at some incredible schools over the years. At Fieldcraft, I usually only throw my hat in the ring to teach hunting or shotgun classes but I couldn’t resist sharing my thoughts on this exquisite pistol in this week’s blog. You might find it fits a need in your life.

The “K”

The first time I saw the SIG MPX was at the SIG Sauer Academy years ago. A student was running one in a rifle course when all the other students were using 16” ARs in either .223 or .300 BLK. The student and the MPX held their own for most of the close-quarter class and I was genuinely bummed I couldn’t own one in Connecticut. Fast forward to my move to Utah (also known as “Free America”) and next thing you know, I have one on order and eventually in my hands. The MPX is their pistol caliber carbine or pistol caliber pistol equipped with a brace. Mine showed up with the side-folding SIG brace and since it is the K (Short) version, it has a 4.5” barrel. The K comes with a 30-round magazine but there are shorter and lower capacity magazines for more concealment. You can look up the manufacturer specs but know this pistol’s footprint is small and makes it an incredible choice for the backpack. Of course, since it comes without any additional features and an empty rail, I had to purchase some accessories for it.

Add Ons

Much like any long gun I own for camp security or home defense, I like having three key features; a light, an optical sight, and a sling. For the MPX-K, I added those plus a couple of extra features. Starting with the light, I chose the Surefire 3V Scout and mounted it at the 3 O’clock position. It has a pressure switch that I ran over the Picatinny rail at 12 and adhered it to the forend at 9 O’clock. This would let me activate it with my left-hand thumb or my right-hand middle finger. This light stays out of the way when the pistol is slung across the chest and provides plenty of white light for reduced-light/no-light shooting. I chose the Trijicon MRO on a Geissele Automatics mount for my dot sight. With hours upon hours of constant on and many reps with this dot, it didn’t make sense to choose otherwise. My Blue Force Gear sling is mounted to the Mlok with QD swivels. Aside from these features, I added an SB Tactical collapsing brace, as well as Bravo Company USA, flip-up HK style back-up iron sights. I chose the telescoping SB Tactical brace over the folder since the MPX has recesses in the receiver for the telescoping arms and it keeps the overall width of the pistol fairly narrow. There wasn’t anything else needed except for a hand stop and M-Lok panels, spare mags, and plenty of ammo. Note: I also acquired a Midwest Industries 13” handrail for this MPX that let me run a SIG SRD suppressor underneath it. At the risk of sounding SIG blasphemous, that configuration gives it a very HK MP5SD appearance.


If you’ve never used a pistol like the MPX-K, it will surprise you. The overall weight makes the recoil feel like you’re shooting a rimfire. It doesn’t have the muzzle flip of a larger caliber firearm and the combination of the short bolt movement and Timney trigger cycles rounds very quickly. The K version of the MPX doesn’t have a lot of real estate to hold onto forward of the magwell but it also isn’t impossible to get a hold of with two hands. Up drills are very quick as the “K” swings with your body. Target transitions with controlled pairs and triple shots are easy to perform with a high level of accuracy. You will absolutely burn through ammunition quickly as it is seriously fun to shoot. Even though it is a pistol caliber, with a red dot and proper holds, 100-yard shots are not out of the question. Thanks to AR-style controls, the MPX-K doesn’t take long to learn if you are transitioning over from that .223 platform. Shooting the MPX-K at night in low-light conditions is interesting too. Since it is a pistol caliber and not an overly gassed round, the muzzle device from SIG keeps flash down significantly. If you are into strict marksmanship, you’ll find the additional points of contact you get out of the brace to make 25-yard B8s an easy target compared to standard pistol shooting.

The Why

I’m a SIG fan. Some would call me a fanatic with the number of classes I took while I lived in New England and others would say I’m a fanboy since I own a couple of 320s and a P365. There is no hiding I like using SIGs and I regret the ones I’ve sold foolishly over the years. The MPX-K isn’t going anywhere and I think it fits a very practical role. It makes a great firearm for a beginner who is recoil shy or one who doesn’t like the concussive blast from a rifle. It legit fits inside of most backpacks that look like backpacks and not like a tactical guy building a backpack that no one believes have camping gear in it. The K is very maneuverable inside the home and I would sooner grab it than a non-pistol braced handgun. Also, the cost of 9mm ammo at the time of writing this was just shy of $20 for a box of 50 while .223 ammo was $12 for a box of 20. Of course, this pistol isn’t a rifle and that is a major criticism of the design. Some would argue there isn’t a place for pistol calibers when 300 black is available. To that, I’ll ask, is it? I love 300 black but it is expensive and I can’t always find it. Kind of like my argument for standard 30 caliber hunting rifle ammo over wildcat rounds, 9mm is an industry-standard you can find just about anywhere.

As long as you know the capability of the MPX-K, you will definitely find a place for it in your collection. So far, mine has run thousands of rounds through it with no issue and I’m learning the best mix of subsonic ammo to use with my suppressor for the quietest shots possible. When I take friends to the range, I often give them the option to try out firearms they don’t own. Almost everyone has said they are going out to get a K too. Perhaps the best conclusion to this blog isn’t an explanation of the why but rather the want. I promise you, if you try this firearm, you’re going to want one too. You can figure out your own needs later.