The bevel of the wedge is the same as the bevel on the bottom of the cutter, ten degrees. This beveled
wedge is pushed forward by a screw. The rear of the rifling head has fine threads and is tapped into the
rear of the rifling head. Turning this screw forward in the rifling head results in pushing the beveled
wedge farther forward under the cutter and raises the cutting edge.
A cut is made in each groove of the barrel before moving the wedge farther forward to raise the cutter
for a deeper cut. The front end of this hook-type cutter, which is three-quarters of the length of the cutter.
This seats against a steel plunger within the tube that has a coil-spring in front of it.
The front end of the cutter is beveled back from the top at about ten degrees. The end of the
spring-backed plunger is beveled at ten degrees in the opposite direction, so that its included angle
with its top surface is 100 degrees. The front end of the cutter is held upward against the top surface of
the rifling head. The cutter is normally about 2 to 2 1/4 inches long over all and the rifling head 6 to 8
inches long depending on the caliber. The top or cutting edge of the hook is cut on a radius to fit the
bore.
The cutting edge of a rifling cutter is ground and honed to a template. When it is resharpen or honed
during the rifling operation its form will not be changed at any point. The cutting edge has to be kept very
sharp and very smooth to do a good job. The barrel steel is tough and tends to tear, rather than cut
clean, unless the tool is kept sharp.
The scrape-type of rifling head leaves a better finish in the grooves than does the hook-type hut it is
more difficult to keep sharp and requires very careful honing to do a good job. Its cuts by scraping rather
than a shearing cut and the shavings are fine.