Sons of Liberty Gun Works Gas Block .750 V2, Gas Block, Nitride Finish, Black GB750V2 Sons of Liberty's V2 gas blocks are the highest quality gas block on the market" while remaining simple to use and affordable. Made of industry leading 4140 steel to match the thermal properties of your CrMoV barrel. Sons of Liberty gas blocks are designed to sit on the gas block shoulder and be screwed down to the dimpled barrel with their knurled head fasteners. They have removed the handguard cap gap from their gas blocks allowing them to sit directly on the shoulder for a more secure fit.