The SIG MP-320 – The Secretive P320 Grip Module

It’s all because of Flux Defense. All of it. What’s it? Well, everything regarding this entire article. First off, they showed that converting a traditional handgun into a PDW can be done effectively, efficiently, and without compromising the gun’s capability. It interested me in the idea of a modern civilian PDW, and I’ve been doing a series on the concept. It was also the Flux Defense Facebook page that introduced me to the SIG MP-320. The MP-320 is not just another grip module from SIG. It’s a unique and radical deviation from the norm, barely advertised or discussed, which piqued my interest.

SIG makes many grip modules, and so do many other companies. However, the Flux Defender Raider series stands out as more than just fancy grip modules. It offers a PDW-sized platform with a spring-loaded brace or stock, a spare magazine holder, and an optics mount. The innovative design of the Flux Raider is a testament to the company’s creativity, and when I saw the MP-320, I couldn’t help but get excited about the enhanced capabilities it brings to the table.

What’s the MP-320

The MP-320 is a grip module that requires you to add your P320 FCU and a complete slide. It’s not a firearm and doesn’t require an FFL transfer. The MP-320 isn’t like any other SIG OEM grip module; instead, like the Flux Raider, it aims to convert your P320 into a big, braced pistol. Into a Personal Defense Weapon, if you will. The MP320 is a grip module, complete with a brace and a top cover that encloses the slide and allows you to add an optic, light, etc, to your firearm.

The MP-320 from SIG aims to turn your P320 into a fairly large subgun. The rear portion of the grip module has a 1913 rail, which makes it easy to attach stocks, sling holders, etc. With an MP-320, you get an AR-type charging handle that connects to a new custom backplate that comes with the MP-320. The system provides a fairly sleek and slick design that offers you plenty of accessorization and converts how the pistol handles.

It’s still a pistol, but it’s a really big one. SIG is selling the MP-320 as a kit. You get the grip module and cover, as well as the PCB brace, charging handle adapter, a 30-round magazine, and even the new SIG ROMEO5 Gen 2. The package will cost 600 dollars, and you’ll have to provide your own slide and barrel. SIG also produced some six-inch threaded barrels to make suppressor use easier, selling for 200 dollars.

Why Haven’t You Heard of the MP-320

The MP-320 was announced three weeks ago, but why haven’t you heard of it? Why hasn’t SIG’s new grip module PDW conversion hit the front page of firearm blogs across the net? Good question. It’s probably because SIG has done nothing to advertise it. It’s not even listed on their website. In fact, you only see it mentioned in one SIG YouTube video.

It’s not even on the main SIG Sauer YouTube channel, but the SIG Academy channel. As of this writing, it sits at a mere 59K views. Also, you can’t purchase it online. It’s only available for sale at the SIG Experience Center. This is where we get into something that’s likely to frustrate some readers.

SIG only plans to produce 800 of these systems. They only produced 200 of the six-inch barrels. Once those 800 are gone, they are gone. This is a bit like the MCX TACOPS and MCX Surge. Once they are gone, SIG will not make any more of them. Why? That’s a great question.

Maybe it’s due to the brace issue? Maybe they will only produce 800 of this version and then produce another version that’s less exclusive? I’m not really sure what SIG plans. The MP-320 seems to be a limited-use item, and maybe it’s just niche enough that it would never demand massive sales.

Better than the Flux?

Comparisons will be immediately drawn to the Flux, which is fair. But is one better than the other? It’s tough to tell without a side-by-side test, but I don’t think it’s a necessary comparison. The MP-320 is larger and heavier than the Flux Raider and doesn’t seem to have the goal of being concealable. The MP-320 and the Flux are a bit like the MP5 and the MP5K. They have different purposes, although they are similar.

Overall, I think the Flux Raider is a bit better thought out and more feature-filled, but it’s interesting to see SIG get into the PDW game in such a limited manner. Will they advertise the MP-320? Are the current buyers beta testers for a bigger product? I can’t say, but SIG seems to be mum on the MP-320 series.

Travis Pike
Travis Pike is a former Marine Machine gunner who served with 2nd Bn 2nd Marines for 5 years. He deployed in 2009 to Afghanistan and again in 2011 with the 22nd MEU(SOC) during a record setting 11 months at sea. He’s trained with the Romanian Army, the Spanish Marines, the Emirate Marines and the Afghan National Army. He serves as an NRA certified pistol instructor and teaches concealed carry classes.