Sig Sauer MCX Rattler LT .300 AAC Blackout AR Pistol — 6.75" Threaded Barrel, Side-Folding Brace
The MCX Rattler LT is Sig Sauer’s newest, ultra-compact take on the MCX platform. Built around a 6.75-inch cold-hammer-forged barrel and a short-stroke gas-piston system, this pistol delivers reliable .300 BLK performance in a package that folds to just 17.1 inches and weighs 5.1 pounds. Full ambidextrous controls, a match two-stage trigger, and a QD suppressor-ready muzzle device make it a versatile choice for personal defense or discreet carry in the field.
Condition
Overall Condition: Excellent condition, showing only faint signs of any prior use or handling.
Specific Condition Notes: Minor superficial scratches and blemishes are visible on close inspection, but the firearm retains a like-new appearance overall. The bore is clean and shiny.
Bore Condition: Excellent – Clean, mirror finish, no signs of wear.
Bore Rifling: Excellent rifling – Sharp lands and grooves.
What’s Included
- Sig Sauer MCX Rattler LT pistol
- 2 × 30-round Magpul PMAG polymer magazines (one marked for .300 BLK, one standard 5.56×45 GEN M2)
The Rattler LT uses Sig’s latest LT upper with a free-float alloy handguard and fully ambidextrous bolt catch/release, magazine release, and safety selector, allowing seamless operation from either shoulder.
A two-position adjustable gas block lets you fine-tune cycling for supers or subsonic loads, and the 1:5 twist rate is optimized for heavier projectiles often used with suppressors.
The cold-hammer-forged carbon-steel barrel is threaded 5/8-24 with a tapered shoulder and ships with a QD suppressor-ready muzzle device, making it turn-key for suppressed or muzzle-device setups.
The side-folding, skeletonized 6061-aluminum brace reduces overall length to 17.1 inches when folded, enhancing portability without compromising quick deployment. A flat-blade, two-stage match trigger breaks at approximately 4.0 pounds, supporting precise shot placement from a compact platform.