CMMG Banshee Mk4 .22LR Dedicated Upper Group (9-Inch)

The 9-inch Banshee Mk4 .22LR upper is the mid-length version of CMMG's dedicated rimfire upper group, built on the same self-contained straight-blowback bolt as the 4.5-inch variant but with a 9-inch 4140CM medium-taper barrel inside a longer EML7 M-LOK handguard. It drops onto any mil-spec AR-15 lower, feeds from CMMG .22LR AR magazines, and ships with the bolt group, an ambidextrous ZEROED charging handle, and a ZEROED flash hider on the 1/2x28 threads.

For a forced reset build the barrel length changes the tuning rules, not the mechanics. The extra 4.5 inches of dwell extracts more velocity from the same round, which pushes an unweighted bolt harder: soft bulk high-velocity loads run well unsuppressed, but hanging a suppressor on this length demands subsonic ammo or added bolt mass to keep the bolt from outrunning the case. The 4.5-inch upper remains the more forgiving forced reset host; this one buys velocity and sight radius for general rimfire duty at the cost of a narrower weightless-tuning window.

Like the short version, building this on a lower configured as a rifle makes it a short-barreled rifle requiring a Form 1 before assembly; a pistol or braced build skips that classification. CMMG lists it at $799.95 MSRP; OpticsPlanet carries 9-inch finishes from $639.99.