Sig Sauer MCX Rattler SBR .300 AAC Blackout, 5.5 in Barrel, Adjustable Gas Piston, Folding Stock, with Suppressor
This Sig Sauer MCX Rattler SBR in .300 AAC Blackout pairs a compact 5.5 inch barrel with an adjustable short-stroke gas piston and a folding, length-adjustable SIG-branded stock. It features a PDW-style upper, a free-float aluminum M-LOK handguard, and a continuous 1913 Picatinny top rail. Included are UTG/Leapers flip-up iron sights, an angled foregrip, and a detachable sound suppressor. This is a double tax stamp setup with an SBR and suppressor.
Condition
Overall Condition: Excellent condition, showing only faint signs of any prior use or handling.
Bore Condition: Excellent - Clean, mirror finish, no signs of wear.
Bore Rifling: Excellent Rifling - Sharp lands and grooves.
Specific Condition Notes: This rifle shows light signs of wear and handling.
What’s Included
- UTG/Leapers flip-up iron sights (front and rear, installed)
- Detachable sound suppressor (installed)
- Angled foregrip (installed)
- 1x 30-round Magpul PMAG polymer magazine
The Rattler configuration centers on a 5.5 inch threaded barrel chambered in .300 AAC Blackout (7.62x35mm), built to run in a compact PDW footprint. The upper is PDW-style without a forward assist and bridges seamlessly into a free-float aluminum M-LOK handguard, providing a rigid, lightweight front end.
Its short-stroke gas piston system is adjustable, with gas-setting markings for quick reference. Controls include an ambidextrous safety selector, plus a right-side bolt catch/release and magazine release for efficient manipulation. The MCX hinge accepts the SIG-branded folding, length-adjustable stock, set up here with a 12.5 inch length of pull.
Mounting and sighting are straightforward thanks to the continuous 1913 Picatinny top rail that spans the upper and handguard. UTG/Leapers flip-up iron sights are installed, and the handguard offers M-LOK slots for accessory placement. An angled foregrip is mounted for added front-end control.
The receiver is aluminum with a hard-coat anodized black finish and carries factory roll marks including "RATTLER" on the upper plate and "SIG SAUER INC., NEWINGTON, NH USA" and "SIG MCX MULTI-CALIBER" on the lower. The rifle is finished in black and is made in the USA. Capacity is 30+1 and it ships with a 30-round Magpul PMAG. This setup includes both an SBR and a detachable suppressor, constituting a double tax stamp configuration.