We start out with either 4150 chrome-moly or 416R stainless steel double stress-relieved bar stock. The bar stock starts out at 1-9/32″ in diameter and 20-24 feet long so we cut it to length.

Step two is to rough-contour the outside of the barrel blank in a lathe.

Thirdly, the blank gets mounted into a Barnes gun drill. The cutter bit has holes through which oil or coolant is injected under pressure to allow the evacuation of chips formed during the cutting process. This is called “oil-through” or “coolant-through”. Without this, you wouldn’t want to even attempt drilling a hole 30” long and under ¼” in diameter. The combination of a 3600rpm and good flushing allows us to drill a beautifully straight and centered hole .005” under “land” diameter at a rate of 1” per minute.

Clean the barrel.

Next the blank is sent back to the lathe to machine the finished contour of the outside.

Clean the barrel again.

Now, the blank is sent on to the Pratt & Whitney reamer in which an “oil through” reaming tool is used to cut away the extra .005” left in the drilling process. The reamer makes an extremely accurate bore size and after it is finished the bore will have a better surface finish and will be at the proper “land” diameter.

Clean the barrel again.

In the sixth step we hand lap each barrel to remove any slight tool marks that may have been left by the reamer and inspect every one with a bore scope. If the barrel doesn’t meet our standards for surface finish and tolerance it doesn’t get any further.

Clean the barrel again.

The barrels then go onto the rifling machine which is responsible for cutting the all so familiar grooves in the bore. A caliber/land configuration-specific rifling head is used to progressively shave away small amounts of steel to form the rifling grooves. This is accomplished by simultaneously pulling the rifling head through the reamed blank as the blank is spun at a controlled rate. After each cut, the blank is rotated 90 degrees (for a four-land configuration) and after one full rotation (360 degrees) the rifling head is slightly raised to shave off the next bit of material. This process is repeated until we reach groove diameter.

Clean the barrel again.

Lastly, the barrel is hand-lapped again (to ensure a smooth bore), and a final inspection is performed with the bore scope.

The barrel is cleaned one last time, wrapped, packed, and shipped to [the customer].