SHOT 2015—SIG Sauer MCX

SIG Sauer MCX with brace

Join any chat board or gun discussion and SIG Sauer will make its way to the top. Known primarily for its pistols’ “To Hell and Back” reliability, SIG Sauer has put the same innovation, reliability and quality assurance into its rifles.

The SIG MCX line features AR-style pistols, SBRs and carbines in .300 BLK! According to SIG Sauer, it is now offering the new MCX line in .300 AAC. Engineered for it and built from the ground up to be silenced, light and short, the MCX series is a breakthrough in modularity. The SIG MCX is proof the dawn of a new era doesn’t happen overnight, but it will revolutionize the way we think about modular rifles going forward.

SIG Sauer MCX Carbine
SIG Sauer MCX Carbine

The SIG MCX is a weapon system built around a battle-proven core: SIG’s gas-operated, short-stroke piston system. For the ultimate in modular flexibility, you can reconfigure SIG’s MCX easily in the field. This makes the operator a true multi-mission threat and ready to handle new challenges in seconds as the battlefield dictates.

The combination of the 13-inch monolithic upper receiver and handguard create a 17.75-inch continuous top rail. The upper is backward compatible with any MIL-SPEC AR lower, allowing you to upgrade your existing AR platform to the SIG MCX. The AR upgrade kit includes a side-folding stock assembly and adapter.

SBX Stabilizing Brace

With a folding knuckle, the SBX improves the single-handed shooting performance of your SIG MCX Pistol. It is also compatible with the SB15. The ATF recently clarified its ruling on the stabilizing brace. Click here to read all about it.

SIG Sauer MCX with brace
SIG Sauer MCX with stabilizing brace

Stock Options

Maximize performance while conserving space with a telescoping or folding stock. Is the length still too much? No worries. The MCX is also available in a pistol configuration for the ultimate in compactness.

AR-Style, Ambidextrous Control

SIG maintained the features and configurations you are already familiar with—no retraining required. The SIG MCX features a familiar AR-style ambidextrous selector, bolt release, magazine release and charging handle.

Rotating Bolt System

The fully locked and closed rotating bolt system on the MCX provides maximum safety and durability. Durability increases by the inclusion of a Nickel Boron coated bolt and carrier.

Short-Stroke Piston

There is not much to say that the title does not already tell you—reduced recoil and fouling with the gas-operated, short-stroke piston system. Nothing beats a short-stroke of course!

Auto-Regulating Gas System

The piston position automatically adjusts based on system pressure allowing the user to switch between subsonic and supersonic ammunition or silenced and non-silenced operation seamlessly.

Upper Receiver

The continuous-to-rail upper receiver features an integral M1913 rail at 12 o’clock and a free-float barrel system.

Quick-Change Barrel

Likely one of the most adaptable features an AR rifle can posses is a quick-change barrel. The MCX quickly and easily adjusts to accommodate a barrel length from 16 to 9 inches.


KeyMod Handguards

A fan of the KeyMod system? The MCX offers a long or short aluminum handguard. For the ultimate looking lightweight rig, the MCX is also available in a carbon fiber and silencer-compatible width.

SIG MCX Carbine
Action Semi-Auto or Select-Fire
Barrel 16.0 inches; 1:6 (300BLK) / 1:7 (5.56 NATO) / 1:9.5 (7.62x39mm)
Caliber 300BLK / 5.56 NATO / 7.62x39mm
Trigger MIL-SPEC; 6.6-8.6 pounds
Overall Length 35.75 inches
Weight Unloaded 6.0 pounds
Operating System Gas piston, rotating bolt
Stock Multiple configurations
Magazine Capacity 30 rounds
Magazine Type AR-15
Forend Type Alloy keymod

Tell us what you think about the SIG Sauer MCX in the comment section.


The Mission of Cheaper Than Dirt!'s blog, The Shooter's Log, is to provide information—not opinions—to our customers and the shooting community. We want you, our readers, to be able to make informed decisions. The information provided here does not represent the views of Cheaper Than Dirt!

Comments (2)

  1. I Took my MCX out of the box. Loaded a 30 round mag into my MCX and began to zero. 26 rounds into it my MCX locks up. Blew the buffer springs into pieces causing them to jam the bolt. AWSOME SIG AWSOME, the first and last time I buy SIG

Your email address will not be published. Required fields are marked *

Your discussions, feedback and comments are welcome here as long as they are relevant and insightful. Please be respectful of others. We reserve the right to edit as appropriate, delete profane, harassing, abusive and spam comments or posts, and block repeat offenders. All comments are held for moderation and will appear after approval.

Discover more from The Shooter's Log

Subscribe now to keep reading and get access to the full archive.

Continue reading