Sig 9mm MPX Pistol PDW ReviewThe Sig MPX is an innovative configurable PDW (Personal Defense Weapon) platform which can be purchased in a variety of forms including pistol, pistol plus Sig Brace, rifle, and NFA regulated SBR format. The model I choose for review is the Sig Sauer MPX Pistol with folding Sig Brace adapter which can be easily purchased just like any handgun on the market and... it's dead sexy.
I feel like porn music should be playing in the background as you read this article complete with an “oohhhhh” and “ahhhh” voice over. The Sig MPX is freaking hot sweaty sexy in a way that gets buyers all too excited to max out a credit card to own one. Yes please, take my money or I will continue licking your gun case. 
Just like that XX video tape your friend sold you as a kid for two months allowance in cash - you really didn’t care how much, or that your dad would kill you if he found it, you were on the verge of ecstasy to see what was on the tape. After the eighth or tenth time, that Dallas based video about Debbie was hardly worth the money. Conversely, I would argue the $1600+ street priced MPX is definitely worth the hefty price... and glaring stare from your significant other. The bonus to ownership is you get to don that creepy grin every single time you put it in your hands and jerk the trigger. WHY A SIG MPX
Of the guns most lust to have, the H&K MP5 is on that list. It is the timeless quintessential 9mm PDW that still serves in many militaries, many law enforcement SWAT teams, and global hostage rescue teams for many reasons - it is utterly reliable, short, accurate, super easy to shoot fast, and pretty hard hitting for a handgun round. We have all built up a mental image of perfection in our minds and all want one. Then you actually fire an MP5 it sadly resembles an accidental meeting years later of “Debbie” the porn star. The looks are still there, but the years of experience are showing with lots of wrinkles, bad skin, heavier than you thought, and indications of a serious high cost substance abuse problem… sadly “Debbie” the new models are hotter. The H&K MP5 is kinda like that. 
As a civilian, you cannot buy a new MP5 so used versions are the only route unless you look at the still astronomically priced Vector or Cohari clones. Original $5000+ MP5s are a bit beat up with a been around the block a few times look, sights are not as user friendly as modern day designs, mag well is not particularly easy to find during reloads, the manual of arms is different from our ingrained AR15/M16 habits that it feels a little weird, there is no last round hold open on most MP5s (some do), optic mounts are goofy, the stamped receiver looks cheap and outdated, replacement parts are getting super pricey, and the price the user pays (if they can find one) is still too high. 
Sorry “Debbie” and H&K, but the dead sexy image from my youth does not match up any longer to what is currently available. In this case, pulling a virgin factory fresh MPX from its box delivers everything I want without the worry of the mileage and cost of an MP5.Despite its reputation and my love affair with H&K, they have made many poor marketing decisions. H&K was in some financial deep water and why they would not do consumer retro releases of some classic guns is beyond me. At a time when $400 Euro H&K P7 trade in guns are going for $3000 on GunBroker.com and shooters are still screaming for a civilian MP5 it seems H&K is leaving money on the table. Why has the semi-auto SP6K (updated MP5 semi-auto pistol) not made it to US shores?
Sig Sauer decided there was money to be made in the MP5 market and developed the MPX to go right after the throat of H&K with a supportable, adaptable, highly configurable, and openly supportable 9mm PDW format. Instead of “me too” product, Sig also addressed all those gripes users had with the MP5 design. If you have always wanted an MP5, the Sig MPX will deliver more grins per dollar and I would argue is…. far better.YOU SEXY THING - SIG SAUER MPX
The Sig Sauer MPX is arguably the sexiest and most titillating thing in decades to come out of Sig Sauer since the MCX was introduced with the same profile but in 5.56 NATO. I mean good lord look at this thing - it is dripping with custom design concepts.
The design perfectly mimics the AR controls, however Sig did not stop there and added full ambi-controls on the magazine release, bolt charging handle, bolt release, and selector switch. Everything you can do with your left support hand, is possible with the right hand. Ambi selectors always annoyingly rub on my trigger finger, however Sig has made the right side selector toggle as short as possible to minimize this known AR15 ambi-selector issue. The charging handle stroke is a bit shorter than your AR15 but it feels similar enough to use this platform for AR15 muscle memory reload drills. All around all the controls are well executed.
Sig made the MPX easy to customize. The new G2 version is fully KeyMod compatible with the plethora of aftermarket keymod accessories. The picatinny spec rail at the rear of the pistol can be left bare, or with just one torx screw a folding or fixed adapter can be used to mount a AR15 compatible cheek stabilizing tube and/or Sig Pistol Brace. If you have received your Form 1 NFA Tax stamp, one of Sig’s fixed, folding or or collapsible stocks can be added. The stabilizing brace adapters offered in fixed or folding models are fully AR15 buffer tube compatible which opens up a world of possible accessories. Even the grip and trigger group are AR15 compatible which means the unique grip and gritty trigger can be easily swapped to something fitting shooter wants and needs. Flexibility is the base of this design.
The MPX is also a caliber convertible platform which can offer users the option to swap out barrels and bolt systems from the factory 9mm Nato, to .357SIG or .40 S&W all just by removing two bolts. I would be shocked and stunned if at some point the public pressure was so great that Sig also had to offer this platform in .45ACP and 10mm - but that is just a hope at this point. 
The heavily flared magazine well makes authoritative insertions fast and easily repeatable. It is a cannot miss reloading port that keeps the MPX happily smacking through 9mm after 9mm round. Honestly, the Sig Sauer MPX is hard to shoot without cracking a giant smile even if you do have to make due with shooting it as a pistol until your SBR tax comes in from the ATF.
Even the magazines are freaking awesome looking. Lancer Systems who is well know for ultra-premium magazines developed the magazine design for the MPX. The mag functioning is smooth and flawless. Reloading rounds is push-in AR style versus slide in handgun mag style which lessens thumb pain.YES THAT IS IT
When you buy an MPX, and you will, make sure you go ahead and get extra mags. I now have six. Also just plan on buying 9mm ammo in 1000 round bulk packs, because otherwise if you only take 50-100 rounds to that first range session you will feel like your hot girlfriend/boyfriend got you worked up and then left you high and dry.
Take all your magazines loaded to the range and make sure you take another 200-300 rounds. I can guarantee that you will not stop shooting until you thumbs are numb from reloading magazines. Instead of metaphorically sexually frustrated, the high round count shooting experience will instead leave you satisfied in a way like that entire weekend you and your significant other spent in bed the first time you told each other you were in love. After just a couple hundred rounds will be ready to sell all your other AR15 pistols and SBRs and commit yourself to the MPX… not today or tomorrow, but ya’know eventually because we are talking about guns here.
Shooting the MPX really does not feel any different than shooting any other AR15 pistol or registered SBR other than the recoil is almost non-existent. Although a completely unfair comparison, by contrast my 9mm Keltec Sub2000 has a sharp little snap but the MPX does not. Sig did a great job with the piston driven gas system to deliver a somewhat cleaner running gun and strip out that jarring snap of the 9mm round hotly existing the longer barrel.
Accuracy is freaking superb. Where the MP5 would really shine were head shots under 75 yards, the MPX shines at this range as well. Hitting my Action Target hostage swinger (6”) at 100 yards was pretty easy also, however I did notice the 9mm round did not have the power to swing the hostage target to the other side at that range. The gun is easily a single ragged hole gun at 25-yards, and at 50-yards 3”-4” for offhand groups were not difficult with quality defense ammo. Heck, with this accuracy, this could be a great little hunting gun.
This is a superb home and personal defense gun complete with KeyMod rail compatibility for lights and lasers. As a Brand Ambassador for Optics Planet, they provided us with the very well made and high quality Hi-Lux Micro Max Red Dot for this build. With the Hi-Lux Micro B-Dot red dot sight added this was a freaky fast little gun that delivered everything I love about .223 AR15 pistols without the deafening report. With a 9mm handgun round going off with your cheek about 20” from the muzzle, you still need hearing protection, however earplugs are all that is needed for outdoor and most indoor shooting. The MPX has a slightly softer handgun report out of the 8” barrel, however it is far from the ear splitting boom an AR15 pistol delivers indoors and outdoors. With the right low penetration ammo such as Federal Guard Dog or the very hot IIIA defeating Liberty Civil Defense 2000-FPS 450-FPE, the MPX delivers accurate high energy dumping rounds combined with limited liability from pass through rounds. For me this gun is starting to make more sense to me as for home and backpack carry personal defense than my AR15 pistols. 
Now that I am also doing some security work, I can see that having a “pistol” with these capabilities in a very small 5.11 pack or messenger bag could be a huge benefit in a mass shooter or hostage situation which required precision shots. The question of whether the non-permanent Sig brace is or is not part of the total length of the pistol’s 26.35” length is a bit of a grey area on whether this gun is considered concealable. It may be advisable to remove the extended sig brace tube and use a standard pistol buffer tube to get the length under 26” if you intend to carry the Sig MPX pistol concealed in a pack.SAND IN THE VASELINE - MPX ANNOYANCES
The price point and accompanying monetary butt hurt allows one to be critical of annoyances. The MPX is freaking expensive. I understand there was a ton of R&D on this gun, however that does not lessen the entry pain when it comes time pay for the MPX. I remember still flenching hard even when buying this MPX from Sig with editorial discount - “Is that ‘with’ my discount?” I asked. The answer was yes, but the tightness in the front of my shorts still pushed the budget by adding four more magazines. OK, so the MPX is still the least expensive option to a reliable MP5 option. At $1600+ with only one mag, the price is barely a third of the way to a pre-ban select fire H&K MP5, but you can still buy the new MPX pistol or Sig brace model just like a any semi-auto pistol.
The magwell is easy to find, however tactical reloads where the bolt is not locked back requires a very firm whack to get them to seat with a full magazine. Although technically a piston driven gas system, and cleaner running than straight blowback operation, this is still one dirty gun after a few hundred rounds. There really is no way around it - handgun rounds equal dirty guns.
For the price… I would have expected a Tritium insert on the front sight post and two included magazines. The polymer dust cover and finger stop booth feel like they will break and any moment, but have not. The dust cover needs to be a bit beefier and I suspect one hard whack in a door jam and it's a goner.
The magazines themselves are selling for $60-$70 which is painful even though they are stunningly well made magazines from Lancer. The trigger is horrible, like… I am stunned Sig Sauer could make something this terrible. How can Sig give me one of the smoothest double action pistols on the market but includes a trigger that feels like it had sand dumped into it. I am glad the trigger is compatible with an AR15 compatible replacement because it is possibly the worst feeling AR compatible trigger ever.
The instructions suck. The ten pages of obvious safety warnings should have been used to tell how to configure everything included in the box. There is a bunch of stuff in the box, the extra QD slung mount took a good hour to understand how and where to attach it as I resisted the urge for an internet search to play the game of "what the hell is this and how do I use it?".
Until you break-in the folding stabilizing brace, which takes about forty or fifty repetitions of feeling like you are going to snap the stabilizing brace off, you could swear that it locks both open and closed. I also found the stabilizing brace length to be about an inch too long to stabilize against the cheek and also about an inch too long to flatly fold against the frame. Swapping to a non-extended carbine pistol tube allowed the folding stock to clear the hand guard and fold flatter. I think the included buffer tube is too long for this application.
FINAL THOUGHTS
Functionally the Sig Sauer MPX is a brick shithouse of durability and is a frontal assault on the MP5 moniker. The MPX had zero functional issues wasting away an afternoon and 1000 rounds of whatever was the cheapest 9mm ammo available in bulk. For those looking to have a 9mm AR15 form factor in hopes of it “paying for itself in cheaper ammo”, the $1600 price tag makes that a bit unrealistic argument at current ammo prices.
Where I do see the MPX making sense is for PDW (Personal Defense Weapon) use. This little pistol can slip into most small packs or messenger bags and delivers a very fast response option with crisp precision which is CCW legal almost everywhere. I would recommend buying a 20-round magazine for this carry option as the 30-rounders are a bit long. The Sig Sauer MPX system screams for SBR stamping and that cool Sig collapsible stock. The MPX was designed for the person wanting a gateway to SBR registration - once you have your SBR Stamp, a stock swap is only one bolt removal away. Buy the MPX like any other pistol, go and shoot it, send in the Form 1 NFA eForm to SBR the gun with a gun stock, and you can still go shoot the gun while you wait for that process to complete.
The Sig MPX is well thought out, totally flexible and configurable for future upgrades. This is an investment firearm which is more than just a toy fun gun. This is also a serious piece of equipment which is perfect for home defense, as a mobile package for personal defense, and as a simple training tool that anyone can use and train from with no worry of recoil. In today’s terroristic atmosphere, I may be carrying this in my pack more to deliver lots of firepower, impressive accuracy, all in a nice reliable little package should the need arise.
SPECS
Item NumberMPX
- Caliber9mm NATO, Converts to .357SIG or .40S&W
- Action TypeSelect Fire or SBR ( LE/GOVT ONLY)
- Operating SystemClosed, fully locked short stroke pushrod gas system
- Overall Length (Telescoping Stock) Closed Min 460 mm/18.1 in
- Overall Length (Telescoping Stock) Open Max 580 mm/22.8 in
- Overall Length (Folding Brace) Closed Min 425 mm/16.7 in
- Overall Length (Folding Brace) Open Max 26.3 in
- Overall Height (with 30 Rd Mag)265 mm/10.4 in
- Overall Width52 mm/2.0 in
- Barrel Length8" in
- Sight Radius270 mm/10.6 in
- FeaturesEasily converts to 9 mm NATO, .357SIG, or .40S&W
- User-configurable stock system: telescoping, folding or pistol configuration
- MSRPNot Available
SOURCES
Sig Sauer - http://www.sigevolution.com/sigmpx
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