CMMG Mk3 Lower Parts Kit | AR-10/.308 | 38CA61A

The CMMG Mk3 Gunbuilder’s Lower Parts Kit provides the core small parts required to assemble an AR-10/.308 lower receiver. It supplies most factory lower-group components while excluding commonly upgraded items such as the fire control group and pistol grip. Parts are intended for use with CMMG Mk3 lowers and are compatible with many LR-308 style receivers; all parts are specified to meet or exceed mil-spec standards.

Typical applications include custom AR-10 builds and precision long-range or target setups where builders prefer to fit their own trigger and grip components.

Product Specifications

• The manufacturer is CMMG.
• The manufacturer part number is 38CA61A.
• The kit is marketed as the Mk3 Gunbuilder’s Lower Parts Kit.
• Compatibility is listed as CMMG Mk3 lowers and most LR308-type lowers.
• The kit caliber is .308 / 7.62 NATO.
• Included components cover most lower-group parts while excluding the fire control group and pistol grip.
• All parts are specified to meet or exceed mil-spec.
• The finish style is black matte.
• The product type is listed as a parts kit.
• Material is listed as various.
• Dimensions are 0.90 x 3.95 x 7.50 inches.
• The manufacturer notes no direct ship to California.
• The UPC is 815835015415.

This kit streamlines the lower assembly process for builders who want mil-spec components and proven compatibility with Mk3 platforms. It provides a practical foundation for assembling a precision AR-10 lower while allowing you to install your preferred trigger and grip components.