Midwest Industries SIG MPX 6.5in Handguard Review

Midwest Industries MPX Handguard EoTech GGG Irons
The author’s MPX SBR with Midwest Industries handguard, Eotech EXPS3 and GG&G back up iron sights.

U.S.A. -(AmmoLand.com)- I am an enormous fan of the SIG MPX; It’s the gun that brought me over to the dark side of converting a pistol into an SBR and donating $200 to the government. It all started back in June of 2014. I had a chance to visit the SIG academy for a media event where we got a chance to run new MPX select-fire SMGs.

At the time, the only three fully-automatic firearms I had ever fired were the Israeli Negev, a MAC-11 and the HK MP5. Based on the MP5 and MAC, I concluded everything I had read about the MP5 being the most pleasant, controllable SMG ever made seemed accurate. So I was skeptical that SIG could touch the king of SMGS – until I fired it. After firing around three magazines in full auto at a steel target some 30 yards away, I felt like the gun was a natural extension of my arm. I could simply point, click and deliver lead with incredible efficacy.

Five mags and a boiling-hot MPX sub-gun later, I was hooked – I had to own one.

Since then, my personal Sig MPX SBR has had between 15 and 20,000 rounds fired through it. I can count the number of malfunctions, and the number of times it has been cleaned on one hand. I changed some parts, reverted others, but all the working components are exactly as they arrived from the factory. In fact, there’s only one thing I’ve wanted to change about the gun – the handguard.

Midwest Industries SIG MPX 6.5in Handguard M-Lok Rail Segment
The Midwest Industries SIG MPX 6.5in Handguard ships with an M-Lok Picatinny rail segment.

While the factory KeyMod handguard has never failed me, the fact that vastly more accessories feature an M-Lok interface than a KeyMod one limits what I can bolt on to the little compact blaster. So a few weeks ago I decided to buy a SIG factory M-Lok Handguard… until I saw the price. Hovering around $200, and out of stock basically everywhere I looked, I decided to try something else. After some searching online, I came across an option from a company that I’ve had great success with before: Midwest Industries.

Midwest Industries SIG MPX 6.5in Handguard

Buy Now Gun DealsRetailing for around $145, these handguards aren’t just cheaper than SIG’s OEM components, they are slimmer and half as heavy. Impressed, I sent off an order for one to Midwest as quickly as I could.

A few days later when it arrived, the handguard had another surprise in store for me: a rail segment. While this might seem slight to most readers, it’s always a nice added touch when a product comes straight from the factory ready to be used. I can imagine a less experienced shooter being disappointed to learn that in addition to buying a handguard, they would need an adaptor for their older Picatinny rail accessories.

Midwest Industries MPX Handguard Streamlight ProTac HLX Laser
The aftermarket handguard has enough rail real estate for shooters to mount large tactical lights like this Streamlight ProTac HLX.

Excited to try out my new toy, I cleared my MPX’s action and removed the old handguard. The new one slid on with no issues whatsoever. The lockup is flawless in terms of horizontal and vertical alignment. The only issue I’ve found is with forward and rearward movement. The handguard can slide an almost imperceivably short distance forward even when everything is bolted down tight. So small was this movement, that I needed a set of small feeler gauges to determine how much. I initially tried to slide a playing card in the gap, but the card was too thick. After breaking out the gauges, I found the movement to be around 0.17mm.

This is a minor annoyance, and in testing had no effect of performance whatsoever. Even when shooting with iron sights, the extra movement provided no apparent change in point of impact. I’m sure an engineer out there will tell me that it does have an effect, but given the limited effective range of a 9mm para round, I’m not worried. Though, just to be sure it wasn’t my gun being out of spec after so many rounds fired, I installed the handguard on an MPX carbine with only 300 rounds fired through it and got the same result. Also, that setup was surprisingly handsome given how far past the handguard the 16in barrel protruded.

Midwest Industries MPX Handguard Spikes Barking Spider
Despite its slimmer profile, the Midwest Industries handguard can accommodate 1.8in or smaller diameter muzzle devices like this Spike’s Tactical Barking Spider linear comp.

One last aspect of the handguard I want to mention is the addition of an extra pair of mounting slots above the standard three and nine o’clock ones. These are excellent if a shooter wants to mount a tactical light a little higher so it doesn’t interfere with their support grip. Especially for shooters like myself who employ their MPX as a home defense weapon.

So, what’s the verdict on the Midwest Industries SIG MPX 6.5in Handguard?

Added functionality, reduced weight and the inclusion of a rail segment for less money than the original makes the Midwest Industries MPX Rail a very appealing product. The only aspect of the gun I wasn’t thrilled with was the slight amount of play along the Z-axis. But given that it has no effect on function or accuracy, it’s one I can live with. Plus, if it really bothers a shooter, they would simply add a bit of JB weld to the rail, and file it down to fit. It might not look pretty, but it would definitely do the job.

Jim GrantAbout Jim Grant

Jim is a freelance writer, editor, and videographer for dozens of publications who loves anything and everything guns. While partial to modern military firearms and their civilian counterparts, he holds a special place in his heart for the greatest battle implement ever devised and other WW2 rifles. When he’s not reviewing guns or shooting for fun and competition, Jim can be found hiking and hunting with his wife Kimberly, and their dog Peanut in the South Carolina low country.

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You just had to throw in that “…I cleared my MPX’s action…” blurb to let everyone know what a responsible gun owner your really are? PA-LESE!!! And being able to detect “…an almost imperceivably short distance…” of “…around 0.17mm.” A space so small that edge of a playing card wouldn’t fit. Really? So you can actually detect a gap that small and then let it annoy you enough to have to comment on it? Since the human hair varies from 0.04 mm to 0.12mm in width, I’d say that makes you slightly “anally retentive” and some serious professional counseling is probably… Read more »


At least we didn’t have to hear his voice as he made the claim. Do yourself a favor and never watch a video where he speaks.


These prices are meant as a joke , right?


Sig should be sued for fraud with the mpx. What is it 7 years after they released it and they still haven’t released the 40 and 357 conversions.
Sig made one hell of a vapor ware with this adds.
Only reason I bought one was because they said they would release a 357 conversion