Button Rifling
A rifling method in which a hard carbide button is pushed or pulled through the bore, ironing the grooves into the steel in a single fast pass.
In button rifling a polished tungsten-carbide button, shaped with the mirror image of the desired grooves, is forced through a drilled and reamed bore under enormous pressure. Rather than cutting metal away, the button displaces and burnishes it, forming all the lands and grooves at once in seconds. The result is a smooth, accurate bore produced far faster than the older cut rifling process allows.
The speed comes at a cost: cold-forming the steel locks stress into the barrel, which can cause the bore to open up toward the muzzle when the blank is later contoured or as it heats during fire. Reputable makers stress-relieve button-rifled blanks before final machining to keep them straight and uniform. Done properly, the method delivers the consistency that precision shooters expect at a price that supports volume production.