A steel shaft will work much better. The steel shaft has a groove on the out side with spiral grooves and
run through an indexing fixture held in a clamp. The barrel to be rifled is clamped in a fixture on the rifling
bench, in the same way as the barrel was held by the above method. The spiral cut shaft is clamped by
two clamps, in line with the barrel to be rifled. One of these clamps, which are also a guide for the spiral
shaft, is plain and the shaft must be a close fit, but must not bind, as it passes through it with a twisting
rotation.
The indexing fixture, which has as many pinholes, that is equally spaced around its circumference, as
many as the desired grooves in the barrel. A harden steel pin fits tightly in these holes, and only one pin
being used, all holes being the same size. This pin passes through the fixture rim and engages the
spiral groove in the shaft.
A ball-bearing handle is fastened to the end of the spiral shaft. On the opposite end of the spiral shaft
from that to which this handle is fastened, the tube that is connected to the rifling head is screwed in
place. Only one groove is cut in the guide shaft. The spiral guide shaft is made about 2" in diameter, if
too small in diameter, it will not move as freely.
A fairly heavy-walled steel tubing may be used for this purpose. The spiral groove can be cut in the
guide shaft with a milling machine, which is equipped with a spiral-cutting setup. The milling machine
must have a table long enough and with enough travel to cut this long spiral.
LATHE FOR RIFLING
The screw-cutting lathe can be used to rifle barrels and the setup is not that expensive. Some makers of
lathes supply spiral attachments for their lathes. These have a set of gears with them and these gears, in
connection with the gears regularly supplied with the lathe, will cut almost any required spiral.