How to Drill & Rifle a Gun Barrel

Written by scott friedman
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How to Drill & Rifle a Gun Barrel
Barrels are the most complex part of a rifle to manufacture. (barrel image by sasha from

The process of turning a long, steel bar into a shiny machined barrel with intricate rifling on the interior is the most complex process involved in manufacturing a firearm. Specialised equipment is necessary to fabricate and rifle a barrel that would not be seen in most other industrial machine shops. There are hundreds of barrel makers across the United States that use equipment of varying complexity, but using the most modern equipment available reduces the chances of ruining a piece of steel while making a barrel.

Skill level:

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Things you need

  • Deep-hole drilling machine
  • Reaming machine
  • Button rifling machine
  • Furnace 1200-plus degrees F

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  1. 1

    Purchase a round bar of steel that is 11/4 inch in diameter and 30 inches long. The best steel you can find for your barrel is 416 stainless steel, but 4140 chrome moly steel will also make an excellent barrel. An industrial steel supplier should be able to provide you with one of the two kinds of steel above in the dimensions required.

  2. 2

    Mount your piece of steel in the deep-hole drilling machine's fixture, which will spin the barrel at more than 2,000rpm when turned on. The deep-hole drilling machine will then push a tungsten carbide tipped blade on a 40-inch rod into the spinning piece of steel at the rate of 1 inch per minute.

  3. 3

    Place your drilled barrel into the reaming machine's fixture and turn on the machine, which will spin a reamer on the end of a lubricated shaft at about 200 to 500rpm. The reamer size is determined by the calibre you want your barrel to be.

  4. 4

    Engage the reaming machine, which will push the mounted barrel into the reamer until it passes through the other side of the barrel. Be sure the mounted barrel and the reamer's shaft are perfectly aligned to manufacture the best barrel possible.

  5. 5

    Mount the reamed barrel in the button rifling machine and then mount a specific kind of button on the machine's rod to carve a certain kind of rifling as well as twist into your barrel. Each button has a different rifling pattern ground into the outside of the button. See the barrel twist calculator in the resources section for more information on choosing a twist ratio for your barrel.

  6. 6

    Lubricate the bore of the barrel heavily.

  7. 7

    Turn on the button rifling machine, which will then pull the button through the lubricated barrel and carve the rifling.

  8. 8

    Place the recently rifled barrel in the furnace at 648 degrees C for about an hour before removing. Stress relieving your rifled barrel is necessary to avoid potential barrel splitting when firing.

Tips and warnings

  • You may want to take this time to machine some threads on the outside of the end of your barrel to allow a muzzle brake or flash suppressor to be attached at a later time.
  • Always be cautious when operating industrial machining equipment and wear safety goggles and gloves at all times.

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