The Sig Sauer SIG MCX-Rattler UPR 6.75" 300BLK BLK upper receiver brings the latest MCX-Rattler LT design to your existing lower, delivering a compact, suppressor-ready platform with modern ergonomics. Its 6.75" cold-hammer-forged barrel is paired with a QD Clutchlok muzzle device and a rigid free-floating handguard, offering smooth handling and consistent performance in a short, controllable package.

This complete upper is designed to adapt seamlessly with most M4/AR-15 spec lower assemblies, making it an ideal choice for shooters who want a compact 300 Blackout setup for range use, training, or personal defense configurations where allowed by law. The adjustable gas system supports optimized use with or without a suppressor, while Sig Sauer’s reputation for precision engineering and innovation is evident in every component of the MCX-Rattler UPR.

Key Features:

• Manufacturer: Sig Sauer
• Model: SIG MCX-RattLER UPR 6.75" 300BLK BLK
• Caliber: 300 Blackout
• Barrel Length: 6.75"
• Unique Features: Adjustable Gas System, QD Clutchlok Muzzle Device, Compatible With M4/AR-15 Spec Lowers