Sig Sauer MCX Rattler Canebrake .300 AAC Blackout AR Pistol, 5.5 in Barrel, FDE Cerakote, Short-Stroke Piston, 1:5 Twist
The MCX Rattler Canebrake is a purpose-built .300 BLK AR pistol configured for suppressed-length handling. This example pairs a 5.5 inch cold-hammer-forged, nitride-finished barrel with an extended SD M-LOK handguard and a factory-installed Inert Training Device that mimics a suppressor's length for training. It features Sig's bufferless MCX operating system with a rear 1913 interface and side-folding brace, a fast 1:5 twist optimized for heavy subsonic loads, and a flat-faced two-stage Matchlite Duo trigger. Finished in FDE Cerakote over 7075-T6 aluminum, it comes with installed SIG flip-up sights and two 20-round Lancer magazines marked 300 Blackout.
Condition
Overall Condition: Excellent condition, showing only faint signs of any prior use or handling.
Bore Overall Condition: Excellent - Clean, mirror finish, no signs of wear.
Bore Rifling: Excellent Rifling - Sharp lands and grooves.
Specific Condition Details: This example shows minimal handling. The bore is bright and the finish is uniform throughout.
What's Included
- SIG Sauer factory cardboard box with matching label (SKU PMCX-300B-5B-TAP-CANE)
- Original manual
- SIG Sauer flip-up front and rear iron sights (installed)
- SIG Sauer M-LOK hand stop (installed)
- SIG Sauer M-LOK rail cover panel (installed)
- SIG Sauer Inert Training Device (ITD) (installed)
- 2x 20rd Lancer L5-AWM polymer magazines marked 300 Blackout
Built on the MCX short-stroke gas piston platform, this Canebrake runs a 5.5 inch cold-hammer-forged, nitride-finished barrel with an adjustable gas block and a threaded muzzle. The fast 1:5 twist is optimized for heavy subsonic .300 BLK projectiles.
The Canebrake's extended SD M-LOK handguard is designed to enclose a suppressor. A factory SIG Inert Training Device is installed to duplicate suppressor length and mass for safe training. The Inert Training Device installed on the muzzle is not a suppressor.
Sig's bufferless internal recoil system and rear 1913 interface allow the included side-folding brace, keeping the package compact. Controls include ambidextrous safety levers and an ambidextrous charging handle for versatile handling.
A flat-faced, two-stage Matchlite Duo trigger provides a defined break, while factory SIG flip-up sights, an M-LOK hand stop, and a rail cover are installed. The receiver is 7075-T6 aluminum with an FDE Cerakote (E190) finish, with markings that include the RATTLER model plate and SIG MCX MULTI-CALIBER. The factory box label (SKU PMCX-300B-5B-TAP-CANE) matches the receiver serial, and two 20-round Lancer L5-AWM magazines marked 300 Blackout are included.