SIG Sauer MCX Rattler .300 AAC Blackout Pistol, 5.5-inch Barrel, Short-Stroke Gas Piston, Adjustable Gas, Folding Brace
The SIG Sauer MCX Rattler is a micro .300 AAC Blackout AR-style pistol designed around a 5.5-inch steel barrel and a short-stroke gas piston system. It features an adjustable gas block, a rear 1913 rail interface with a side-folding brace that can be fired while folded, and a hard-anodized alloy construction. A continuous top Picatinny rail and an installed three-prong flash hider round out its compact, purpose-built configuration.
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: This firearm is in great shape. There are some minor and superficial scratches and blemishes present.
What’s Included
- 1x 30-round Magpul PMAG for 300 BLK (polymer)
- Original SIG Sauer owner's manual
The Rattler’s short-stroke gas piston action is paired with a 5.5-inch steel barrel and a threaded muzzle capped by a three-prong flash hider. The adjustable gas block supports tuning the system for different ammunition and operating conditions within the .300 AAC Blackout platform.
A rear 1913 rail interface supports the side-folding polymer brace, and the pistol can be fired while folded. Overall length is approximately 23 inches extended and about 16 inches folded, with a weight around 5.6 lb for easy carry and storage in a compact form factor.
Controls are thoughtfully configured, including ambidextrous safety and bolt catch with a standard magazine release. The pistol uses a short free-float handguard and a continuous top Picatinny rail. A SIG-branded polymer pistol grip provides a familiar interface.
Capacity is 30+1 in .300 AAC Blackout (7.62x35mm). Markings include a “RATTLER” plate, “SIG MCX MULTI-CALIBER” logo on the magwell, and a “MULTI-CAL” ejection-port cover. Made in the USA with hard-anodized alloy receivers and finish.