MAKING RIFLING BUTTONS

The invention of the rifling process using a swaging button to impress the rifling into solid metal has
been the biggest boon to the barrel making industry since the invention of gunpowder. Where it normally
took hours to rifle, a barrel now it will only take seconds.

Button rifling is a cold forming process in which a small carbide button or swage, with lands cut in the
button. It pulled through the gun barrel bore embosses the rifling in the bore. The button is made a few
thousands larger than the finish size that is required, since the metal will return .001 to .0015 thousands.

Button rifling is a surface forming process; no metal is removed in the rifling process. With button rifling,
barrels can be rifled much more efficiently and much cheaper than any other process except possibly
with hammer rifling, or forging.

All rifling styles can be duplicated by this method. Oddball rifling styles that would be difficult to attain
with any other type of cutting or scraping process can be easily done with carbide swaging process.
Button rifling will give a much smoother, harder, and more uniform bore than can be obtained with cut
rifling, and in turn give much longer barrel life.

On cut rifling the barrel has to be shot several hundreds rounds to get lapped in, or has to be lapped by
hand to get top accuracy.

With button rifling, the barrel will shoot from the very first, and there is no wasted shots trying to get it to
group good. The old way of rifling that was done in the past hundred or so years was done with single
cutters.

They cut out each groove separately, and required several passes to remove the required of metal. It is
an extremely slow process and the finish so produced is not that good.

The main improvement in cut rifling came just about at the start of World War 1. This was the start of
using broaches. Since far more metal must be removed from the grooves than can be cut out with a
single broach, a series of broaches, each a trifle larger than its predecessor was used. This varied in
number from 15 to 50, and could be pushed or pulled through the bores.

These gang broaches are formed from a single piece of tool steel. Gang broaching, although much
either faster than the older single cutter method or single broaching is costly in tools. Gang broaches are
difficult and complicated to make, expensive to keep sharp, resharpen, and easily damaged.

With button rifling, you can rifle the hardest barrel steels, with very little difficulty. It produces the
smoothest and most uniform surface yet attained. A single pass is sufficient to finish the entire bore.
The button is difficult to fashion accurately and is sensitive to breakage. Nonetheless simple and
normally has a long life.