The X37 Series Muzzle Brakes combine JMAC's effective RRD muzzle brake design and a direct thread mount for several popular suppressors as well as our BDS-37 and BDS-37-EXT blast shield! This allows you to leave the muzzle device installed and simply thread the suppressor over! Reduces weight, length, and cost compared to QD systems. Direct thread is also the preferred mounting method for accuracy! Product Specs: 14-1LH Threads X37 - 1.375-24 External Threads 10mm Bore 17-4ph Stainless Steel Black Nitride Requires timing for proper function. Not intended or recommended for barrels shorter than 10.5" (see below) When testin Mfg: Jmac Customs