Sig Sauer Upper Receiver Assembly Sig MCX Rattler 5.56x45mm NATO 5.5″ with Tapered Lug M-LOK Handguard Black

Convert any MIL-SPEC AR Lower into a MCX Rattler with this Sig Sauer Upper Receiver Assembly. Complete with upper assembly, lower receiver stock adapter kit, side folding AR buffer tube knuckle, and match duo trigger kit.

Rapid deployment, thin, agile, and precise. This is the MCX Rattler. Featuring a 5.5″ PDW barrel, side folding AR buffer tube knuckler, and match duo trigger kit, the MCX platform has never been more compact or accessible. Ready to go where-ever it’s needed. This upper receiver was designed from the ground up to be as discrete as possible while retaining all the capabilities of the MCX. Free-floating M-LOK handguards matched with a PDW upper, the MCX Rattler upper receiver is the ideal choice for fast-moving operators.