Description
The SIG Sauer MCX Spear LT 9" 300 Blackout Upper lets you upgrade your existing platform to the pinnacle of short-stroke piston technology. Purpose-built to optimize the legendary terminal ballistics of the .300 AAC Blackout cartridge, this complete upper receiver assembly combines a compact 9-inch barrel with a durable Flat Dark Earth (FDE) finish.
Designed to attach to any standard AR-15 lower receiver using the included stock adapter kit, this assembly delivers military-grade reliability, suppressor-ready performance, and modularity in a lightweight package.
The Evolution of the Short-Stroke Piston
-
Cooler, Cleaner Operation: Moving gas away from the bolt carrier means carbon and debris don't vent into the receiver. This significantly cuts down cleaning intervals and boosts component life.
-
Two-Position Gas Regulator: Instantly tune your rifle for subsonic or supersonic ammo. It manages backpressure effortlessly, whether running unsuppressed or with a silencer.
-
Rock-Solid Handguard System: The Spear LT updates the handguard attachment method to be completely rigid, eliminating flex and ensuring your lasers, lights, and indicators hold zero under hard use.
Optimized for the Subsonic Threshold
A 9-inch barrel is widely recognized as the ballistic sweet spot for the .300 Blackout cartridge. It provides full powder burn for maximum velocity with supersonic rounds while keeping the overall length compact and highly maneuverable when paired with a suppressor. The muzzle comes equipped with the SIG Sauer quick-detach flash hider, making it ready to host your favorite SLX or SLH silencer right out of the box.
