I would say gain-twist rifling on the 460 S&W could be equated to a free-bore type run and, after speaking with Cylinder and Slide, I am certain my own 460 S&W revolver has a modest .005 barrel-cylinder gap. Ralph goes over and measures everything when charged to do anything to your firearm. That is how he found the excessive barrel-cylinder gap on my 500 S&W that he was also working on for me along with the 460. He called me when he discovered it on my 500 and we talked over the options. I am very happy with Cylinder and Slide and they stand behind any work they do with their lifetime warranty. You cannot beat the service or the results.