I hear that they make them under the name of Weatherby too.
I turn the tool upside down and run the chuck in reverse cutting from the shoulder to the breech. Light cuts but you can cut faster speeds.I cut some external ones on an older Grizzly and had to keep the lead screw engaged. PITA against a shoulder. I wouldn't want to do it on internal threads on that lathe.
As far as changing them to English, there's a lot to be said against bastard rifle parts.
Just started doing this. Much better than trying to stop perfectly in the relief. I just threaded a barrel for an extension for my 1879 Trapdoor that I converted into 257 Roberts.I turn the tool upside down and run the chuck in reverse cutting from the shoulder to the breech. Light cuts but you can cut faster speeds.
My wife tells me I have too much S###, I tell her there's no such thing, just don't have enough room for all my S###........ TMS ( Too Much S###)