This is a SilencerCo Endcap known as the Bravo Front Cap chambered in 556NATO, model AC1341.
The Bravo Front Cap is compatible with Omega 300 and Hybrid 46. Swap out the Anchor Brake for an overall shorter silencer from 7.09" to just 6.06". Using correct front caps will reduce dB levels between 2-5 dB.
Features:
Can reduce dB levels between 2-5 dB
Using front cap shortens silencer OAL