The M18-1 thread is made from 17-4 Precipitation Hardened stainless steel, heat treated to H900. This brake has an integral lock nut with a left hand thread to allow easy and accurate clocking for the brake. The 2 Port Brake will provide moderate recoil reduction when used without a suppressor and provides a very sturdy mount for the 338LM suppressor using both the conical section in the rear as well as the parallel section in the front for maximum concentricity.