Broach Rifling
A cutting method that pulls a long, progressive multi-tooth broach through the bore, finishing every groove to full depth in a single pass.
Broach rifling is a refinement of cut rifling built for speed. Instead of a single point that must make many passes, the tool is a long bar carrying rows of teeth that grow progressively taller from front to back. As the broach is pulled through the bore one time, each successive tooth deepens the cut a little more, so all the grooves reach full depth in one stroke.
Because the broach removes steel rather than displacing it, the bore comes out with relatively low stress like other cutting methods, yet far quicker. This combination of cut-quality grooves and high throughput makes broaching a common choice for mass-production barrels. The finished lands and grooves are sharp and clean, though the tooling itself is expensive and must be kept in precise condition.