SIG MPX: Video and Details

SIG MPX video

“The next generation of submachine gun is here,” states a SIG Sauer video demonstrating the all new SIG MPX.  The SIG MPX is a new submachine gun that the company is expected to show off at next week’s SHOT Show.

There are a number of features that really set this gun apart from others in this category.  First, according to the video, the SIG MPX is the world’s first submachine gun to work with a fully closed and locked rotating bolt system.  The gun uses the SIG Sauer short stroke gas piston system that the company has used on their other rifles.  There is a last round hold open.

(Ed. note:  A huge thank you to Scott for sending me a link to this video.)

Something else that is pretty distinctive about the SIG MPX is a shooter can quickly change barrel lengths, caliber and stock configurations in the field.  When you watch the video, you will see someone swapping out a barrel fairly quickly.  According to the company, the SIG MPX is “an entire system that can be configured for any operation.”

SIG MPX barrel swap

The gun will be available in multiple configurations.  Select fire versions are limited to government buyers in the United States, but several semi-auto versions will be offered also.  One will be a short barrel rifle (SBR) configuration with a 6.5″ barrel and telescoping stock.

The other semi-auto version has a 6.5″ barrel with a permanently attached 9.5″ long muzzle brake.  If you take a look at the photo below, you will see the muzzle brake is essentially a wide open skeleton that appears to be more about getting around the stupid National Firearms Act and less about decreasing muzzle rise.  Frankly, I love it.

SIG MPX-C carbine

The SIG MPX will be available in three pistol calibers:  9mm, .40 S&W and .357 SIG.  I’ve speculated before that this gun chambered in .357 SIG would be a great SMG.  The .357 SIG rounds are already fast out of pistols.  With a slightly longer barrel (6.5″ instead of 4″ or 4.5″), one could expect them to be even faster.  Using the data at Ballistics by the Inch, I would guess that a standard Federal 125 grain JHP would jump up about 150 fps by shooting it from a 6.5″ barrel.  At about 1550 fps, that round would likely defeat soft body armor.  For a SWAT team, this might make an excellent alternative to the MP5 and AR15 platforms.

Meanwhile, I am going to try to get a carbine version for review.  Shooting a SIG MPX  is going to be a blast!

SIG MPX bolt

SIG MPX magazine

SIG MPX review





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About Richard Johnson

Richard Johnson is a gun writer, police trainer and really bad joke teller. Check out his other writing in Combat Handguns, Guns & Weapons for Law Enforcement, on The Firearm Blog and at BlueSheepdog.


  1. I can’t wait to get my hands on the carbine version!


  3. I’ve never wanted a full auto gun so badly in life…

  4. The SIG MPX and SIG MCX are looking like fine pieces of engineering. Can’t wait for the releases. Time to stock up on ammo,magazines, and new range toys. Stoked.


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