Cut Rifling
The oldest rifling method, in which a single-point cutter removes metal to form one groove at a time. Slow and costly, but it leaves the bore stress-free.
Cut rifling is the original way to put spin in a barrel: a hook or scrape cutter passes down the bore many times, taking off a few ten-thousandths of an inch per stroke, indexed around the axis until every groove is finished. The process forms the lands and grooves by removing steel rather than displacing it, so the surrounding metal is never compressed or work-hardened in the way other methods cause.
Because no material is forced sideways, a cut-rifled barrel carries almost no built-in stress and tends to stay dimensionally honest as it heats and cools. The trade-off is time and money, since one barrel can take an hour or more on the machine. For that reason cut rifling has long been prized by a slice of match-barrel makers, while higher-volume shops favor button rifling.