This is a SilencerCo Mount known as the Charlie, model AC622.
The ASR (Active Spring Retention) Mount is a quick attach / detach system for almost all SilencerCo suppressors. The simple one-hand-on" one-hand-off mounting system is compatible with all ASR Muzzle Devices to promote ease of transfer from one silencer to another. Once shouldered" the locking ring ensures the silencer won't rotate or work itself loose under a heavy firing schedule.
Features:
Charlie accessories are compatible with Chimera 300, Omega 36M, and Saker ASR (all models)
