The BRDE Universal gas block drilling jig is a combination of blocks used to set up barrels to drill many gas block/barrel assemblies. The set requires exposed gas block journal in front of the gas block to index. If this is not the case, you may still use the blocks but will need a backer plate and clamps (not included) to index the front block. If your gas block has a pilot hole or flat already drilled, it may not align with this jig's drilling arm. You will have to set up on the opposite side of the pilot OR remove the guide arm and use the jig set to setup the assembly in a drill press.
This jig set includes a rear block drilled and keyed to fit the barrel extension, a 0.750 bore front block, 0.625 bore front block, 0.875 front block and a 0.936 bore front block. If the barrel is already installed in an upper, you may still use the front block by squaring to the upper on a flat surface. The bushing is housed in a 1/2" OD collar. This jig works great with a hand drill. You may want to use a 3mm end mill to pilot drill, depending on the situation.
Cold rolled carbon steel
Manganese Phosphate finish
#31 drill bushing in the guide arm
Includes 2 1/4"-28tpi x 3/8" soft point set screws, one for the rear block and one for the front block
Includes one #31 cobalt jobber drill bit and 1/8" and 3/32" hex key