Sig Sauer MCX Spear-LT .300 Blackout 30 Round 9" Barrel. The MCX platform has long been SIG SAUERS breeding ground for developing the best rifle system in the world through extensive testing, continued innovation and customer feedback. Now SIG SAUER Introduces the SIG SAUER MCX-SPEAR-LT Rifle, a revolutionary firearm built upon the legacy of its predecessor, the MCX Virtus. Designed with cutting-edge technology and precision engineering, this rifle sets a new standard for performance, versatility, and user experience."/\