This adapter will allow you to mount 5/8x24 RH muzzle devices to a barrel with a M13x0.75 RH thread pattern. The production and inspection process is optimized to ensure best possible fit and concentricity between both threads and through hole. It offers two large flats for tight installation and preserves the full front shoulder for squaring and securing the muzzle device. Machined to accept 7.62/.30 cal rounds and smaller.