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How to Drill a Gas Port in a Barrel

Hobbyist gunsmiths were disappointed when the Bureau of Alcohol, Tobacco, Firearms and Explosives halted importation of rifle barrels with AK-47 parts kits. Parts kits originally included all parts of the rifle except the receiver (the foundation of the gun) and the parts that allow the gun to fire in fully automatic mode; that is, continuing to fire when the shooter holds the trigger down. Hobbyists were able to assemble the parts into a new, U.S.-made receiver to build a legal semi-automatic (only one shot per trigger pull) copy of the AK-47. New rules require that the builder purchase a new U.S.-made barrel and drill the gas port (which taps off high-pressure gas to operate the rifle) to fit his parts kit.

Things You'll Need

Ball peen hammer
Drift punch
Scratch awl
Center punch
Cobalt or high-speed steel drill bit, 5/64 inch
Black electrical tape
Drill press with vise
Rifle cleaning rod
Steel or bronze bore brush, .30 caliber
Gun cleaning solvent

Instructions

- 1
  Slide the gas block (from the parts kit) onto the barrel. Use the hammer-and-drift punch to tap it into position.
- 2
  Reach into the gas-block passage with the scratch awl. Tap the handle of the awl to mark the barrel.
- 3
  Tap the gas block back off the barrel. Place the center punch on the scribed mark and strike it with the hammer to deepen the mark.
- 4
  Measure 1/4 inch up from the tip of the drill bit, and wrap tape around the bit to mark the drilling depth. Place the drill bit into the drill-press chuck. Tighten the chuck.
- 5
  Clamp the barrel into the drill-press vise so the mark on the barrel is under the drill bit. Tilt the drill-press table 45 degrees so the chamber end of the barrel is higher than the muzzle.
- 6
  Squirt cutting oil on the bit. Switch the drill press on and slowly advance the bit to drill a hole in the barrel on the mark. Stop when you reach the taped depth mark on the bit.
- 7
  Remove the barrel and clean it with the cleaning rod, bore brush and solvent.

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