The Hawkins Precision Tank Brake was designed for long-range shooting in the prone shooting position. It reduces recoil and muzzle rise without stirring up a lot of dust leaving your field of view open for another shot. The Tank Brake is one of the most efficient muzzle brakes on the market, this brake reduces felt recoil by 5/8-24 3B more than half. Ideal for big boomers!! Available in Stainless steel and 4140. Diameter .875, Flats .750″, threads 1/2-28 3B .  This brake needs to be installed by a qualified gunsmith.