New Manufacture Gas Blocks for 416 Type Barrels & Firearms These new production 416 type Gas Blocks are machined from billet steel to provide long life, during the most extreme use. To ensure high performance, the Gas Blocks are machined from 4140/42 steel then finished with an extremely hard & lubricious black nitride finish. The interior of the gas block that accepts the piston head is finely machined & honed to prevent any machine marks and ensure smooth operation. Tab at the rear of the gas block ensures proper alignment with the barrel every time, allowing for proper gas flow. Gas blocks require the use of 416 type coil pins for proper installation. Only compatible with 416 type barrels (not compatible with standard AR15 or M16 barrels or gas block journals).