SIG MCX Spear LT 11.5" 5.56 Conversion Kit

The SIG MCX Spear LT represents SIG Sauer's third-generation MCX platform, incorporating lessons learned from the NGSW program and addressing criticisms of the heavier second-generation Virtus. This conversion kit drops onto any standard AR-15 lower receiver, giving shooters access to the MCX's short-stroke piston system without committing to a complete rifle purchase.

The defining characteristic of the MCX platform is its self-contained recoil system housed in the upper receiver, eliminating the need for a buffer tube. This enables side-folding stock capability—the 11.5" Spear LT collapses to just 21.3" overall length, making it exceptionally compact for vehicle storage or transport while maintaining full 5.56 NATO terminal performance.

The Spear LT shaves roughly one pound compared to the Virtus through a slimmer handguard profile and lightened barrel. The 11.5" configuration strikes an ideal balance between maneuverability and barrel velocity, producing effective terminal ballistics to 300+ yards while remaining highly compact. The short-stroke piston runs significantly cleaner than direct impingement systems, extending maintenance intervals and making it an excellent suppressor host.