And when that happens, you can obtain a fired case and have a reamer and gages made from it. Then, have your gunsmith of choosing do the work for you.
That is what is known as intellectual theft. While it is not unlawful, it is dishonest.
Kirby goes to a lot of trouble and expense to test his cartridges and the rifles that will shoot them. There is a lot of hidden costs that most people don't see like testing different barrels and different brass but people like me and Dick have a reasonable understanding of it. When you steal his ideas and have someone else build a rifle you have failed to pay for Kirby's hidden costs and have cheated him.
The chief reason I don't have Kirby build more of my rifles is I am just really paranoid about shipping my guns around. If a person does good work for you then you should show appreciation by customer loyalty.
Finally, if there lots of gunsmiths who can build great long range rifles around why don't you see their names mentioned when hunting season rolls around and pictures are posted and proof is laid out for all to see.