The CMMG Banshee Mk4 Upper is a complete 22 LR assembly designed for standard AR-15 lower receivers. It features a 4.5 4140CM steel barrel with a 1:16 twist and Salt Bath Nitride finish. The Armor Black Cerakote receiver is paired with an EML4 M-LOK free-float handguard. This system includes a bolt carrier group, a ZEROED Ambidextrous Charging Handle, and a ZEROED Flash Hider. It is engineered to use CMMG 22 AR conversion magazines, offering a compact and reliable rimfire solution for the AR platform.