CMC Triggers Ejection Port Cover Assembly Fits AR 15 Black CMC DC STD UPC 810169562505
Product Description
The CMC Triggers® Ejection Port Cover Assembly in Black (SKU: CMC-DC-STD / UPC: 810169562505) is a heavy-duty, factory-spec replacement dust cover kit designed to seal and protect the upper receiver chamber on AR-15 and M4 platform rifles. Engineered to shield critical bolt carrier group components from dirt, sand, mud, and environmental debris, this essential component ensures complete operational reliability in harsh tactical field conditions.
Manufactured from high-strength stamped steel and treated with a durable black oxide finish, the CMC-DC-STD resists surface corrosion, scratch wear, and thermal stress under heavy firing cycles. The kit comes fully complete with all necessary mounting hardware—including the steel ejection port door, hinge pin, steel detent, detent spring, and high-tension torsional spring—providing a seamless solution for new upper receiver builds or replacing worn factory dust covers.
Designed to fit all standard mil-spec forged and billet AR-15 upper receivers, the door spring opens instantly upon the initial rearward movement of the charging handle or bolt carrier group, guaranteeing unobstructed cartridge ejection.
*Armorer Bench Notes & Real-World Staging Guidance:*
Fitment Matrix: Direct drop-in fitment for all standard mil-spec forged and billet AR-15, M4, and M16 upper receivers. Will NOT fit AR-10 / LR-308 large-format upper receivers, nor will it work with non-standard PCC uppers lacking ejection port hinge pin lugs.
- Ensure the host upper receiver is completely clear, magazine removed, and chamber visually and physically verified empty.
- Slide the ejection port cover hinge pin partially through the forward receiver lug, installing the door and placing the torsional spring onto the pin body.
- Wind the long arm of the torsional spring one full turn (180 degrees counter-clockwise) against the interior door face to provide positive tension.
- Push the hinge pin fully through the rear receiver lug and secure it with the included C-clip (if applicable) before function testing snap closure and automatic carrier release.
Key Features
- Mil-Spec AR-15 Fitment: Precision-molded steel geometry mounts cleanly to all standard mil-spec upper receivers.
- Complete Assembly Kit: Includes steel dust cover door, steel hinge pin, spring, and spring detent hardware.
- Corrosion-Resistant Black Oxide Finish: Matte black surface treatment protects against moisture, sweat, and environmental wear.
- High-Strength Stamped Steel: Rigid steel construction prevents warping or bending under heavy field use.
- Positive Spring-Loaded Detent: Holds door firmly closed until cycling bolt carrier group automatically pops it open.
- Ideal for Builds & Replacements: Perfect drop-in component for custom AR-15 upper receiver staging or repair.
Product Specifications
- Brand: CMC Triggers®
- Model/Series: Ejection Port Cover Assembly (Dust Cover)
- MPN / SKU: CMC-DC-STD / CMC-DC-STD
- UPC: 810169562505
- Platform Compatibility: AR-15 / M4 / M16 Upper Receivers
- Material: Stamped High-Strength Steel
- Finish/Color: Black Oxide / Matte Black
- Included Hardware: Dust Cover Door, Hinge Pin, Torsional Spring, Detent & Spring
- Country of Origin: United States
