Sig Sauer’s name may be synonymous with handguns for many gun owners, but they make other guns, too. Among their popular models is the Sig MCX Virtus Pistol, the pistol-length version of a rifle that Sig states can be configured in more than 500 combinations. Here’s the thing: although this is an AR-15 type gun, it is technically its own gun (which is why Sig refers to its “AR-15-like features”).

The team at 1911 Syndicate covers the specifications and performance of this pistol in this review and goes into some detail about what sets it apart from the most common AR-15 platform guns.

Sig MCX Virtus Details
So, what exactly sets this pistol apart from the AR-15 it appears to be? According to the guys at 1911 Syndicate, this is what you need to know:
“It’s like an AR-15, but it’s not an AR-15, right? The reason for that is that it is a piston-driven gun, specifically a short-stroke gas piston, and we will get into that. When you see it at first, and you’re like…it’s clearly an AR, is what you think…it has AR controls, between safeties and mag releases, bolt releases, all that kind of stuff.
“You see the handguard, and the handguard is really your first clue something is going on there. The handguard is interesting looking and there’s different things going on up here, and really what you’re seeing is the piston design and some of the modular [stuff] we will get into. Once you start getting into this gun, [it is] definitely not an AR, it’s just very AR inspired, if you will.”

Why would you want a piston-driven rifle?
There are a few reasons given in the video:
- More interchangeable/configuration friendly than some platforms
- Suppressed use
- Military applications
- Cleaner-running
- Greater longevity and durability
Bottom Line
This is a tough pistol to get your hands on, but if you can find one it is worth the time and effort. It’s backed by Sig Sauer’s reputation and has a variety of features to recommend it.
This pistol is available in two calibers: 5.56 NATO and 300 BLK — with the 300 BLK being slightly lighter weight and shorter. Features of the 5.56 NATO model include a 7.4 pound empty weight and an overall length of 31.0 inches.
When choosing calibers, first consider the pistol’s use. 300 BLK was specifically designed for close-quarters work while 5.56 NATO was made for longer distances. However, this is a pistol platform with shorter barrels, meaning you won’t be getting the same range out of the 5.56 NATO model you would in a rifle-length gun. Compare the ballistics of the two calibers out of the barrel lengths they’re offered in and go from there.
Sig MCX Virtus Specifications
- Caliber: 5.56 NATO
- Barrel Length: 11.5 inches
- Capacity: 30-round magazine (ships with)
- Magazine Type: AR-15
- Action Type: Semi-automatic
- Stock Type: PCB
- Barrel Material: Cold hammer-forged carbon steel
- Trigger Type: Matchlite Duo
- Twist Rate: 1:7
- Forend Type: Alloy
- Grip Type: Polymer
- Receiver Finish: Gray
- Overall Length: 31.0 inches
- Overall Width: 2.8 inches
- Height: 8.0 inches (no optic)
- Threads: 1/2 inch-28 TPI
- Accessory Rail: M-LOK
- Operating System: Gas Piston
- Weight: 7.4 pounds (empty)
- MSRP: $2335