SIG Sauer MCX-R Regulator 5.56 NATO Semi-Auto Rifle – 16-Inch, Short-Stroke Piston, Gen II NiR FDE Cerakote
The MCX-R Regulator brings SIG’s proven short-stroke piston system to a fixed-stock carbine optimized for both suppressed and unsuppressed fire. Early-2024 production examples like this one ship with a Gen II NiR Flat Dark Earth Cerakote finish that lowers infrared signature, an ambidextrous control set, and a free-float handguard featuring an integrated ARCA rail for direct tripod mounting. Crisp two-stage match trigger, two-position gas regulator, and cold-hammer-forged barrel round out a feature set tailored to serious shooters who value reliability and modularity.
Condition
Overall Condition: Excellent condition, showing only faint signs of any prior use or handling.
Specific Condition Notes: Light handling marks are present but do not affect function or appearance.
Bore Condition: Excellent – clean, mirror finish, no signs of wear.
Rifling Condition: Excellent – sharp lands and grooves.
What's Included
- 1× 30-round sealed Magpul PMAG Gen M3
- 1× 10-round polymer AR-pattern magazine
- Magpul SGA cheek-riser kit (FDE) for fixed stock
- Blue Force Gear Vickers Combat Applications Sling
- Factory paperwork and manuals
- Original SIG Sauer cardboard shipping box
Built around SIG’s battle-proven short-stroke gas piston, the MCX-R Regulator runs cleaner and cooler than direct-impingement designs. A two-position gas regulator lets the shooter quickly tune the cycle for suppressed or unsuppressed fire, enhancing reliability across different setups.
The 16-inch cold-hammer-forged carbon-steel barrel is threaded 1/2-28 TPI and ships with a two-port brake for flat recoil management. Coupled with a 1:7 twist, it delivers consistent accuracy with both 55- and 77-grain 5.56 NATO loads.
Gen II NiR Flat Dark Earth Cerakote covers the 7075-T6 upper and proprietary lower receiver, providing corrosion resistance and reduced infrared signature. The lower accepts a Magpul SGA shotgun stock while maintaining compatibility with standard MCX uppers for future caliber or barrel swaps.
The free-float aluminum handguard offers M-LOK slots along its length, a full Picatinny top rail, and an integrated ARCA-Swiss rail for direct tripod mounting—ideal for precision or night-vision work. Ambidextrous magazine release, safety selector, and charging handle support both right- and left-handed shooters.
A flat-faced two-stage match trigger breaks at a clean 4.5 pounds, and the fixed polymer stock includes QD sling cups, length-of-pull spacers, and cheek-riser compatibility for fast shooter fitment.