...My motive is to settle the matter for everyone.
Or, as they say in another er,
sport, "Let's settle this once and for all."
Except they don't. Risky here, too. Make sure that anyone who volunteers is willing to say, after the test, that the results settle things, rather than "yeah but."
I suspect that will cut down on takers considerably in the long range game. There will still be the yeah buts; no testing will ever banish them.
Larry Costa would be fine for point-blank. Or any of the past or present WBC shooters. I'm sure there are others, but these guys have proven they both go and succeed with what shows on paper. Host country supplies powder... the WBC in South Africa was a "challenge," as I remember
As for the testing itself: worth noting would be Harold Vaughn,
RAF, pages 75-76, "Accuracy Testing,"as well as pages 235-36, "Statistical Error."
(Another interesting test would be to do it twice. Once with a very, very good barrel someone's willing to sacrifice 50-rounds out of it's life, and once with an average, club-match level barrel.)
Edit:
I just had another thought. I'm perfectly willing to believe you can sometimes find a long-range load where .1 grains matters. Scott Fletcher did just that with his .30 Boo-Boo and 240 Sierras. He proved it to his satisfaction (he's an engineer), so I tend to believe him. I further believe it's a lousy load -- a window that small. Unless you also believe that
NO changes in conditions require a change in load (does anyone believe this?), you're better off with a load where the window is considerably broader. I suppose that's
my "yeah but..."