Shop › SCO THRD OVR MZZL BRK 1/2X28 .30 CAL SCO THRD OVR MZZL BRK 1/2X28 .30 CAL $79.90 SilencerCo Compact Radial Brake, 30 Caliber, Fits 1/2X28, Compatible with SilencerCo Thread Over Mounts AC5232 Add To Cart Added! SilencerCo Compact Radial Brake, 30 Caliber, Fits 1/2X28, Compatible with SilencerCo Thread Over Mounts AC5232