The CMMG Mk4 stripped lower receiver (part no. 55CA102AB) gives builders a proven receiver for the CMMG Mk4/AR15 platform, finished in an Armor Black coating. Chambered for the .223 Remington/5.56 NATO family, it ships stripped with no internal fire-control parts installed, so you choose the trigger, safety, and furniture for your build. It is a straightforward, no-frills option for shooters building on CMMG’s Mk4 platform.

Key Specifications

• Chambered for .223 Remington/5.56 NATO on the CMMG Mk4 platform.
• Finished in Armor Black for a durable, mil-spec appearance.
• Sold as a stripped lower receiver, so no internal fire-control parts are installed.
• Runs a semi-auto action, firing one round per trigger pull with standard AR-15 components.
• Ships at a light 0.745-pound shipping weight, keeping freight costs low for a parts order.
• Machined from forged 7075-T6 aluminum for mil-spec strength.
• Armor Black finish is applied as a durable Cerakote coating for corrosion resistance.
• Compatible with standard mil-spec AR-15/M4 lower parts kits.
• Accepts standard AR-15/M4-pattern magazines.

Frequently Asked Questions

Does this lower include a trigger or other internal parts? No, it ships stripped, so you supply the fire-control group, buffer tube, and grip of your choice.

What caliber is this lower built for? It is chambered for the .223 Remington/5.56 NATO family on the CMMG Mk4 platform.

What finish does this receiver have? It is finished in Armor Black for a durable, mil-spec look.

Buy the CMMG Mk4 Stripped Lower Receiver, Armor Black

Order this CMMG Mk4 stripped lower receiver from our Lubbock, Texas gun shop for fast, insured shipping to your FFL, and start your build on CMMG’s proven Mk4 platform. Browse our full selection of AR15 lower receivers for more build options.