Sig Sauer MCX-Rattler LT .300 AAC Blackout Micro AR Pistol with 6.75 in Threaded Barrel and Side-Folding Brace
This Sig Sauer MCX-Rattler LT is a micro-size AR pistol chambered in .300 AAC Blackout and built around the MCX short-stroke gas piston system. It features a 6.75 in cold hammer forged steel barrel with 5/8-24 threads, a 1:5 twist rate, and an adjustable gas system. The pistol is finished in black anodized on the alloy receiver, frame, and handguard, and it includes a top Picatinny rail plus M-LOK/Picatinny handguard interfaces.
Condition
Overall Condition: Excellent condition, showing only faint signs of any prior use or handling.
Mechanics: Mechanically excellent; no known issues. (As always, firearms should be inspected by a qualified gunsmith prior to firing.)
Bore Condition: Excellent - Clean, mirror finish, no signs of wear.
Bore Rifling: Excellent Rifling - Sharp lands and grooves.
Finish Condition: Excellent overall finish condition.
Grip Condition: Excellent overall grip condition.
Specific Condition Notes: The firearm shows little sign of prior use and is in excellent condition and function.
What's Included
- Original factory box (SIG SAUER, SKU PMCX-300B-6B-LT-PCB)
- Original manual
- Cable lock
- 1x 30-round magazine (Magpul PMAG GEN M3 AR 300 B, 7.62x35 / .300 BLK)
Configured as an MCX-Rattler LT pistol, this example combines a compact 6.75 in barrel with a side-folding brace that includes hook-and-loop strap areas. The listed dimensions include an overall length of 25.4 in, a folded length of 17.1 in, a width of 2.25 in, and a height of 7.4 in, with a listed weight of 5.1 lb.
The MCX-Rattler LT uses a semi-automatic, short-stroke gas piston action and an adjustable gas system, giving the shooter a tunable setup based on the firearm's configuration. This pistol is also noted to have no forward assist.
Up top, the receiver includes a full-length Picatinny rail for mounting compatible accessories, and the alloy handguard provides M-LOK/Picatinny interface options. Markings include "RATTLER" and "SIG MCX MULTI-CALIBER," with right-side receiver markings reading "SIG SAUER INC / NEWINGTON / NH USA."
Details on the barrel and muzzle are clearly defined: a cold hammer forged steel barrel with 5/8-24 muzzle threads, a 1:5 twist rate, and a three-prong muzzle device installed. The trigger is described as a flat-faced, flat blade match trigger.