Sig Sauer 8901313 MCX SPEAR-LT 5.56 NATO 11.5" Replacement Barrel & Gas Block AssemblyThe Sig Sauer MCX SPEAR-LT 5.56 NATO 11.5" Replacement Barrel & Gas Block Assembly, identified by the part number 8901313, is a specialized component designed for the MCX SPEAR-LT rifle platform. This Sig Sauer 8901313 assembly includes an 11.5-inch barrel and a gas block, serving as a direct replacement or upgrade part. The 5.56 NATO chambering ensures compatibility with standard ammunition, and the assembly is crafted to meet Sig Sauer's quality and performance standards. It is likely sought after for its compact barrel length, suitable for applications where maneuverability and a shorter overall firearm length are desired.*Please Note: All NFA rules apply to the installation of these upper assemblies to lower receivers and caliber exchange kits to upper receivers. Upper assemblies and caliber exchange kits with barrel lengths less than 16" may only be affixed to lower receivers that (1) are not recorded as a rifle lower by the manufacturer and do not have a stock attached to the lower receiver or (2) registered with the BATFE as a short-barreled rifle (SBR). Please check with your local and state municipalities for any further regulatory requirements. It is your responsibility as the buyer of these components to make sure you comply with all NFA rules and applicable laws. Sig Sauer MCX SPEAR-LT 5.56 NATO 11.5" Replacement Barrel & Gas Block Assembly 8901313