Sig Sauer MCX Rattler Canebrake .300 AAC Blackout AR Pistol, 5.5" Barrel, Coyote Cerakote, Folding Brace
The MCX Rattler Canebrake is Sig Sauer’s purpose-built, suppressor-ready variant of the compact MCX platform. This example pairs a 5.5-inch nitride-treated carbon-steel barrel with a factory 5/8-24 inert training suppressor to deliver the correct balance and gas pressure for subsonic loads right out of the box. Ambidextrous controls, a two-position gas system, and a folding brace make it an adaptable choice for shooters who value maneuverability without compromising reliability.
Condition
Overall Condition: Very good condition, showing only light, superficial signs of prior handling or use.
Bore Condition: Good – Clean, well-maintained, minor wear marks.
Bore Rifling: Good Rifling – Intact, well-defined lands and grooves.
Specific Condition Notes: Light handling marks are visible on exterior surfaces; no corrosion or deep scratches observed.
What’s Included
- One 30-round Magpul PMAG polymer magazine
- Flip-up front and rear iron sights (installed)
- SIG Sauer thread-on inert training suppressor (installed)
The short-stroke gas-piston MCX system keeps the recoil assembly inside the upper receiver, allowing the coyote-colored brace to fold flat without affecting function—ideal for storage and transport.
A two-stage, flat-blade match trigger breaks at approximately 4.5 lb, giving the shooter a predictable, repeatable pull for accurate follow-up shots.
The 1:5-inch right-hand twist rate is optimized for heavy subsonic .300 BLK bullets, while the two-position gas valve lets the user switch between suppressed and unsuppressed settings to maintain reliable cycling.
Ambidextrous safety, magazine release, and bolt catch, combined with the SD M-LOK handguard and full-length top rail, make the Rattler Canebrake easy to configure for right- or left-handed operation with lights, lasers, or optics.
Introduced in 2019, the Canebrake variant was designed around suppressed use, matching the balance of a live can when the included inert trainer is installed—no extra tuning required before adding a real suppressor.