Long term durability and quality tolerances make this gas block from Forward Controls Design an easy choice for your next build. Machined from high strength 4140 chrome moly steel with a military tough magnaese phosphate coating, the GBF is built with a series of surprising features you won't find in most other gas blocks on the market. For armorers and high-volume shooters, the front of the gas block features a 3/32 hole, allowing a punch to easily drift out a gas tube that has been stubbornly seized in place with carbon build up. For maximum security, the GBF features bosses on both sides that allow perfect positioning for a gun smith to pin the gas block to the barrel with either 5/32x5/8 or 1/8x5/8 pins.