CMMG 9MM EJECTION PORT COVER KIT

Description

Pistol-caliber and rimfire AR builds present a specific problem at the ejection port: the rearward position of the bolt in a blowback or conversion setup leaves a gap behind it that standard dust covers are not designed to address. CMMG’s Ejection Port Cover Kit with Gas Deflector is built for exactly that situation, covering the opening left by .22 LR uppers and conversion kits where a standard AR-15 dust cover would leave exposed space at the rear of the port.

The kit ships as a complete assembly — port cover, rod, spring, and a combined gas and brass deflector — so there is nothing to source separately. On blowback-operated builds, spent gas and ejected brass tend to come back toward the shooter more aggressively than on a standard rifle, and the integrated deflector redirects both away before they become a nuisance. This matters more when shooting suppressed, where gas volume at the port increases substantially.

Installation follows the same basic process as a standard dust cover, though the gas deflector adds a fitment step that requires some patience to seat correctly. Once assembled and properly clocked, the cover snaps open on recoil and closes when manually pushed, behaving like any mil-spec port cover. CMMG backs it under their Lifetime Quality Guarantee, consistent with the rest of their parts line.

This kit is specific to CMMG .22 LR uppers and AR-pattern conversion kits — it is not a drop-in replacement for a standard AR-15 port cover used with centerfire rifle calibers.