Nice job, Edster. Good luck on the real one. 416 is very nice to machine though. What kind of tooling are you using? Laydown threading tools would be the best, with angle shims to get the clearance that you need on the insert. Such animals are available.
I would recommend that you have a 'centered pass' in between every cut on alternate thread flanks. It makes quite a difference when the tool is only cutting on one edge at a time. The least of my worries, if I was working a difficult job, would be debating whether I must write out a longhand program that would cut exactly the way I envisioned, or whether I would settle for a general purpose macro that was less than exactly what I wanted.
First you get good, then you get fast. Then grouchiness sets in.
(Note: The opinions expressed in this post are my own and are not necessarily those of CNCzone and its management)