Sig Sauer MCX Rattler Canebrake .300 AAC Blackout AR Pistol, 5.5 in Barrel, FDE Cerakote, Short-Stroke Piston, Folding 1913 Brace
This factory MCX Rattler Canebrake is built around a 5.5-inch .300 AAC Blackout barrel paired with an SD-length, free-float M-LOK handguard and the SIG Canebrake inert training device installed to mimic a suppressor’s size and weight. It features the SIG Matchlite Duo two-stage flat-blade trigger, ambidextrous controls, and an internal recoil system that enables a side-folding 1913-interface brace. Two-tone FDE Cerakote receivers and a segmented 12 o’clock top rail with short Picatinny sections and an open/M-LOK-style gap between complete this suppressed-use-focused configuration.
Condition
Overall Condition: Very good condition, showing only light, superficial signs of prior handling or use.
Bore Overall Condition: Excellent - Clean, mirror finish, no signs of wear.
Bore Rifling: Excellent Rifling - Sharp lands and grooves.
Specific Condition Notes: There is some mild wear and carbon buildup. This Canebrake configuration is intended for suppressed use; do not fire without a suppressor or the included inert training device installed to protect the support hand.
What’s Included
- 1x 30-round Magpul PMAG (polymer, windowed)
- SIG Canebrake inert training device (installed inside SD-length handguard)
- M-LOK hand stop (installed)
The MCX Rattler Canebrake uses a semi-automatic, short-stroke gas piston system with a rotating bolt and an internal recoil system, allowing the side-folding brace without a buffer tube. It is configured from the factory for suppressed operation, and the included inert device maintains the intended length and weight for proper hand placement.
The SD-length aluminum handguard is free-floated and M-LOK compatible, with a segmented 12 o’clock top rail: a short Picatinny bridge at the rear and a separate forward Picatinny section, interrupted by open/M-LOK-style slots; it does not form a continuous rail across the handguard. No iron sights are fitted, providing a clean rail for mounting as desired.
Controls are fully ambidextrous, including safety selectors and magazine releases, with a left-side bolt catch. The trigger is SIG’s Matchlite Duo two-stage, flat-blade match unit for precise control.
Construction features aluminum-alloy receivers with FDE Cerakote (E190) and a darker SD-length handguard for a two-tone look. The coyote-tan brace mounts to the 1913 rear interface and folds to the side. The barrel has a 1:5 twist, and capacity is 30+1 rounds.
Overall length is approximately 29.3 inches (about 21.0 inches folded), and weight is approximately 6.8 pounds with a magazine. Markings include the RATTLER nameplate and a lower receiver marked MULTI-CALIBER with the circular SIG logo. Made in the United States.