Sig Sauer MCX-R Regulator 5.56 NATO, 16 in Cold Hammer Forged Threaded Barrel, FDE, Short-Stroke Piston, Ambi Controls
The MCX-R Regulator brings Sig Sauer's short-stroke gas piston system together with a 16 inch cold hammer forged, threaded barrel and a factory SIG three-port compensating muzzle brake. Finished in Gen II NiR FDE Cerakote over aluminum receivers, it features a free-float M-LOK handguard with a continuous 1913 Picatinny top rail and an optics-ready setup with no sights installed. Ambidextrous controls, a two-stage match trigger, and a proprietary Regulator lower with a built-in Arca section and MCX upper compatibility round out a configuration aimed at modern performance.
Condition
Overall Condition: Excellent condition, showing only faint signs of any prior use or handling.
Bore Condition: Excellent - Clean, mirror finish, no signs of wear.
Bore Rifling: Excellent Rifling - Sharp lands and grooves.
Specific Condition Notes: Shows very little evidence of prior use or handling.
What’s Included
- Sig Sauer MCX-R Regulator 5.56mm rifle
- One 30-round windowed Magpul PMAG polymer magazine
The 16 inch carbon steel barrel is cold hammer forged with a 1:7 twist and factory threaded, and this rifle comes with a SIG compensating three-port muzzle brake installed. The setup supports common 5.56 NATO loads and provides ready muzzle-device compatibility.
The aluminum alloy receiver set wears a Gen II NiR FDE Cerakote finish intended to reduce infrared signature. A continuous 1913 Picatinny rail spans the receiver and free-float M-LOK aluminum handguard, providing straightforward mounting for optics and accessories.
Controls are fully ambidextrous, including the safety selector, magazine release, and bolt catch. An AR-style T-handle charging handle and a two-stage match trigger support consistent manipulation and a refined trigger press.
The proprietary Regulator lower is compatible with any MCX upper and integrates an Arca rail section ahead of the magwell. The fixed polymer stock includes spacer-adjustable length of pull with a recoil pad; this example measures a 13.0 inch LOP. The platform accepts detachable AR-15/STANAG pattern magazines, and capacity is 30+1.