SIG Sauer MCX Rattler Canebrake .300 BLK AR Pistol, 5.5 in Threaded Barrel, Coyote Tan, Folding PCB Brace
The MCX Rattler Canebrake pairs a compact 5.5-inch .300 AAC Blackout system with SIG's short-stroke gas piston and a multi-position adjustable gas block. This variant features the extended SD-style handguard that is designed to enclose a suppressor, a continuous 1913 top rail, and ambidextrous controls. It also includes SIG flip-up sights, the Matchlite Duo two-stage flat trigger, and a two-tone coyote tan receiver with a black handguard and tan folding PCB pistol brace.
Condition
Overall Condition: Very good condition, showing only light, superficial signs of prior handling or use.
Bore Condition: Excellent - Clean, mirror finish, no signs of wear.
Bore Rifling: Excellent Rifling - Sharp lands and grooves.
Specific Condition Notes: The exterior shows a few minor scratches and small blemishes from prior handling.
What’s Included
- 1x 30-round magazine (Magpul PMAG Gen M3 300 BLK, packaged)
- 2x 20-round Lancer L5-AWM 300 BLK magazines
- Two-tone adjustable web sling with QD swivels
- Owner's manual
- SIG Sauer factory box with PMCX-300B-5B-TAP-CANE label
This MCX Rattler Canebrake runs a short-stroke gas piston system with a multi-position adjustable gas block, tailored to the .300 BLK cartridge. The 5.5-inch, threaded barrel and 1:5 twist deliver a compact package with modern gas tuning and dependable piston-driven operation.
The SD-style aluminum handguard is extended and designed to enclose a suppressor, with M-LOK attachment slots for accessories. A continuous full-length 1913 Picatinny rail spans the receiver and handguard for seamless mounting of the included SIG flip-up front and rear sights.
Controls are fully ambidextrous, including the safety selector and magazine release. The Matchlite Duo flat two-stage trigger provides a crisp, predictable press. A 1913 rear interface supports the folding PCB pistol brace finished in tan, complementing the coyote tan receivers and black handguard for a distinct two-tone look.
Additional details include a polymer SIG pistol grip, a 30+1 capacity, and clear factory markings: the right upper receiver is marked "RATTLER" and the ejection port area is marked "MULTI-CAL." The box label confirms the SIG SKU/MPN PMCX-300B-5B-TAP-CANE. Made in the USA.