An assumption I would make though, and probably a pretty safe one, is that Manson’s or Kiff’s action truing kit is likely a money maker for a real gunsmith in terms of time saved while producing a very quality product.
Those systems save time for the gunsmith and therefore are a money maker. The only problem the "very quality product" isn't actually true when they get finished. A tap will follow the hole (you know the hole that's not on center and radially out as well) no matter how many bushings are guiding it. There's only one way to get it right and it's not with a tap.
