Hexagonal rifling an anyone tell me how Whitworth rifling was mad

[Len Graves]

Can anyone here tell me how Whitworth rifling was made? I I know it polygonal but how was it achieved? Was it broached , cut, or buttons waged? Or possibly a process I don't know about. Thanks Len graves

 

[Pete44ru]

AFAIK, for making polygonal-rifled barrels, the barrel (and hence the bore) is cold hammer forged around a mandrel, creating swells or mounds in straight lines, after which the barrel is twisted, giving the bore a defined rate of twist, then machined on the outside (round or octagonal).

 

[Len Graves]

I was perhaps too vague in my question. Did Joseph Whitworth make his rifling in the manner you describe? I think It was just the beginning of the Industrial Age, but I couldn't find any documentation on how HE did it. I know about hammering in rifling but thought it modern. It also seems twisting the barrel would be Frought with problems. I appreciate your reply .