Gemtech 5.56mm Muzzle Brake 1/2-28 - 12152. 56mm Aug M13x1mm Rh Specifications for Gemtech G5 Quickmount 5.56mm: Caliber: 5.56mm Option: AUG M13x1mm RH Muzzle Brake threaded 1/2-28 Flash hider threaded 1/2-28 FNC 9/16-24 LH HK M15x1mm RH Mk18 1/2-28 (for 10.3 barrels) FN P90 M12x1mm LH RUGER 9/16-24 RH Package Contents: Gemtech G5 Quickmount 5.56mm The Gemtech G5 Quickmount 5.56mm is a quality addition to the Gemtech lineup. For more great deals on Flash Hiders by Gemtech please browse our Gemtech Gun Parts page.