Note on Melonite or Nitride Parts

Melonite or Nitride treated barrels and gas blocks have a very hard surface. Standard HSS drill bits that are included with out tools are not hard enough to cut this surface. If you are dimpling or drilling for pinning, you will need hard tooling. I have had mixed luck using cobalt drills. In this application, I recommend using carbide drills. They are substantially higher cost but in the end will save much frustration. We try to keep the #31, 11/64" and 3/16" carbide drills in stock.


What do I need to pin my gas block?

You will need to install the gas block on the barrel and retain with the set screws. I recommend installing on dimples since this will time the gas block with the gas port and will in some cases get the set screws flush with the bottom of the gas block. You will need the jig that matches your gas block. Our jigs are generally hand fit to a sample gas block. Included with the jig is a HSS #31 drill. With the gas block installed on the barrel you can install the jig on the gas block and drill with the included HSS #31 drill or separately purchased carbide drill on nitride/melonite barrels or gas blocks.  With this all done you will need the following to complete.

Pin and matching reamer: You can choose from solid 2/0 taper pins, solid 1/8" dowel pins or 1/8" heavy duty coiled roll pins. With the 2/0 taper pins you will need a 2/0 taper reamer to ream the hole to accept the pin. Care must be taken to not to ream too deep. With either the 1/8" dowel or coiled roll pin, you will require a 0.1247" dowel pin chucking reamer.

On the Geissele gas block, you will use a 3/16" drill to drill for the pin included with the gas block.


How do you use the set up blocks?

The set up blocks are a meant for someone with a drill press or milling machine. They are especially useful for gas blocks that are pilot drilled, as you can set up on a drill press table and use the pilot hole to drill the block. Example of blocks with pilots are Geissele, SLR and Superlative.  


What is the difference between the standard and PRO jigs?

The standard dimple jigs are heat treated for wear resistance, the PRO dimple jigs have replaceable hardened drill inserts on the drilling side. These are press fit and can be replaced when worn.

The standard drilling jigs are not hardened. The PRO jig has a hardened drill insert on one side that is retained by a set screw.


How do I verify what drilling jig fits my gas block or get a custom drilling jig made?

Unfortunately with all the various manufacturers of gas blocks we don't know always know what fits what. To compound the problem, the manufactures can change the specs as well. If you want to know what jigs fits, please provide the following dimensions.

  • Overall Height
  • Width at the barrel bore (outside diameter)
  • Width at the gas tube bore (outside diameter)

With that information we can generally provide the correct jig or quote a custom jig. A photo can also help to make sure there isn't any other anomaly that needs to be accounted for.