The fact that the NRA measured scoring ring increments in inches (the standard distance measurement in the U.S. for that scale of measurement) in no way implies that 1 MOA is an inch at 100 yards. It just means that the NRA chose to use inches (which was really the only logical choice) for laying out their target dimensions.John, the original inch per hundred yards for MOA numbers was established a century ago by the NRA target scoring rings spaced in inches a target ranges in hundred yard increments.
I agree. Which is why all this: "That was cause for sight makers to make them move in amounts ... the mount spacing." doesn't really mean much. The nominal sight adjustment amounts are all just that--nominal.Remember your internally adjusted scope doesn't move the line of sight per click exactly as claimed. Neither does any other. The same make and models don't all adjust the same, either.
It's certainly convenient that 1MOA and 1" are fairly similar in magnitude at 100 yards, but it doesn't mean that they're equivalent.
What's even more amusing than thinking of benchresters--whose hallmark is extreme precision in every respect--being happy with an approximation that's in error by about 5% is to think that if the U.S. had adopted the metric system in the early 1800s, this discussion would be about the validity of approximating 1 MOA at 100 meters as 3 centimeters. (Which, by the way is actually a better approximation--it's only in error by about 3.1%.)