Sig Sauer SIG MCX-R Regulator 5.56 NATO Semi-Auto 16” Short Stroke Rifle
SOLD FOR: $1,576.00
LSB#: LSB260525GM008
Make: Sig Sauer
Model: MCX-R Regulator (RMCXR-556N-16B)
Serial Number: 74A005191
Year of Manufacture: 29-JUN 2024 (Box Label) / Modern
Caliber: 5.56 NATO / .223 Remington
Action Type: Semi-Automatic, Short-Stroke Gas Piston
Barrel Length: 16″. 18″ with muzzle brake.
Sights / Optics: The top of the rifle is a monolithic picatinny rail.
Stock Configuration & Condition: The buttstock is an FDE Magpul SGA 590 stock. The handguard is a 10″ M-LOK rail. The LOP measures 13 1/8” from the front of the trigger to the back of the buttpad. The stock rates in Excellent condition with light handling wear. Has ambidextrous safety and magazine release.
Magazine Quantity & Condition: One 5.56×45 PMAG 10rd in Excellent condition.
Type of Finish: Gen II NiR FDE Cerakote, Coyote
Finish Originality: Original
Bore Condition: The bore is bright and the rifling is sharp. There is no erosion in the bore. In this writer’s opinion the bore rates 10/10.
Overall Condition: This rifle retains about 99% of its metal finish. The balance of the finish shows little to no operational wear. The screw heads are sharp and pins are unmarred. The markings are clear. Overall, this rifle rates in about Excellent condition.
Mechanics: The action functions correctly. We did not fire this rifle. As with all used firearms, a thorough cleaning may be necessary to meet your maintenance requirements. Has ambidextrous safety.
Box, Paperwork & Accessories: This rifle comes with its factory box, cheek piece, two spacers, owner’s manual, and plastic gunsleeve.
Our Assessment: Introduced in 2024, the SIG Sauer MCX-R Regulator adapted the MCX’s bufferless short-stroke gas-piston operating system to a traditional-stocked “ranch rifle” configuration. Rather than using the conventional pistol-grip and shoulder-stock arrangement associated with the MCX family, SIG designed a new aluminum lower receiver around the Magpul SGA 500/590-pattern stock while retaining MCX upper compatibility, a rotating closed bolt, two-position gas system, M-LOK handguard, ambidextrous controls, and a proprietary two-stage match trigger. The 5.56 NATO RMCXR-556N-16B was the optic-ready version, built around a 16″ cold-hammer-forged 1:7″ barrel and SIG two-port compensating muzzle brake.
This June 2024 example remains in Excellent condition, retaining approximately 99% of its original finish with a bright 10/10 bore and correctly functioning action. Its Coyote/FDE treatment, Magpul SGA stock, 10″ M-LOK handguard, ambidextrous controls, factory 10-round PMAG, and included stock spacers make this a notably complete example of one of SIG’s more unconventional modern MCX configurations. The traditional ergonomics combined with the proven MCX piston system give the Regulator a character entirely its own, making this exceptionally clean example an interesting addition for the SIG collector as well as a capable modern sporting rifle. Please see our photos for a better understanding of the condition and good luck with your bids! – L.S.