SIG MPX vs. MCX | What’s the Difference?

The SIG Sauer MPX or the SIG Sauer MCX? Which one should you get?

While the two weapons do share the same gas piston system, they are still two completely different platforms. But both are excellent firearms with good quality, as has come to be expected by SIG Sauer.

Both are also in great demand, to the point that many gun owners wonder if either the MPX or MCX are discontinued. The truth is neither are discontinued, but both are selling so much that SIG is having a difficult time keeping up.

SIG MPX - Wikipedia

This is exacerbated by the fact that firearms and ammunition have been in greatly increased demand this year over previous years, so if you do find an MPX or an MCX for a good price, you would be wise to act quickly to snatch it up.

In this guide, we’ll go over the MPX and the MCX respectively to help you determine what would be the best option you.


The SIG Sauer MPX is a gas operated pistol that is chambered for the 9mm. Under current Federal law, United States civilians can only own the semi-automatic version.

The MPX was first released in 2015, and quickly gained attention due to its closed rotary bolt design. It also utilizes a short stroke gas system that intrinsically reduces recoil.

The MPX also comes standard with an 8 inch barrel with a collapsible stock and a free floating rail. However, variants with barrel lengths from 4.5 inches up to 16 inches are also available. The charging handle is based off of the AR-15 design and is located at the rear of the receiver. The free floating barrel helps to promote accuracy, and M-LOK mounts on the Picatinny rail make it easy to add lasers, grips, optics, and so on.

Finally, the closed bolt design helps to keep debris and grime out of the action while the weapon is in use.


The SIG Sauer MCX utilizes the same gas piston design as the MCX but is still a completely different weapon. Whereas the MCX fires pistol ammo, the MCX fires rifle ammunition such as the 5.56 or the ,300 Blackout. It’s available in pistol, SBR, carbine, and rifle length versions.

SIG MCX - Wikipedia

The short stroke gas piston design is transferred over the MCX and is designed to reduce recoil and reliability drastically. It will accept the standard 5.56 STANAG magazines that the AR-15 uses when it is chambered in that caliber.

The crown at the end of the barrel of the MCX is tapered in order to make it easy to add muzzle devices or sound suppressors. The barrel can also be swapped out easily with other calibers in a matter of seconds. Each MCX barrel is also nitride coated for added rust and corrosion resistance.

Another big benefit to the MCX is the fact that with the aid of an adapter, the upper receiver can be merged with the standard lower receiver of an AR-15.

Which Is Right For You?

At the end of the day, going with an MPX or an MCX is dependent on whether you want a pistol caliber or rifle caliber weapon. The MPX is the more compact firearm, and can be a good choice for close quarters home defense or as a vehicle gun.

The MCX, while a bit larger in the carbine and rifle forms, can still tap targets out at longer distances. However, the pistol sized version of the MCX is very similar in size to the MPX and would likewise be a good option for close quarters self-defense as well.

But at the end of the day, the MPX and MCX are incredibly similar platforms that share common design features. One is designed to shoot pistol ammunition and the other to shoot rifle ammunition.

For those fans of SIG MCX, you can expect a very exciting 2021 ;).


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Written by Sgt. Gunner

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