Thanks for the link, Bob.
I have two pistols and a custom 22-250 AI with hexagonally rifled barrels. The hexagonal rifling came on the pistols. I liked the way it shot so well I went on a pilgrimage to find a 22 caliber rifle barrel because I couldn't get one made 35 years ago.
I found the barrels in Argentina on an electric Gatling gun and after some challenges got one for my rifle build. Very nice but today's crop of match grade barrels shoot just as well if not better — of course my barrel wasn't match grade it was military electric Gatling gun grade.
Ed