AAC (ADVANCED ARMAMENT) BLACKOUT FH 51T 5.56MM 1/2×28#

Description

The AAC Blackout Flash Hider is the foundation of AAC’s Blackout suppressor system, designed for 5.56mm and .223 rifles running standard 1/2″-28 muzzle threads. Its primary function is dual: it works as a standalone flash hider in its own right, and it serves as the dedicated mount for any AAC suppressor built around the 51-tooth ratchet interface.

The 51T designation refers to the 51-tooth indexing collar machined into the device. That ratchet system allows a compatible Blackout suppressor to lock on and detach without tools, and the tooth count is fine enough that the suppressor returns to the same rotational position each time — keeping point of impact consistent across removal and reattachment cycles. This is a meaningful practical advantage over thread-mount systems, where re-torquing to an identical position is not guaranteed.

The flash-suppressing geometry uses an open-ended three-prong arrangement. A closed-end design traps propellant gas and carbon at the prong roots, which accelerates erosion at that junction over time. The open-ended configuration vents that gas forward, which is why AAC chose it for a device that will see sustained use on short-barreled rifles where muzzle blast and flash are more pronounced. Three prongs rather than four also means each tine has more cross-section and is less prone to bending under the mechanical stress of suppressor cycling.

The device is machined from a high-strength aerospace steel alloy and finished in AAC’s SCARmor coating — a hard, corrosion-resistant surface treatment well suited to field conditions and repeated suppressor attachment cycles. Rocksett thread-locking compound is included to prevent the hider from backing off under use.