Well said stuff Mac,
There's a topic on another forum that was titled "How much run-out?" that became a huge discussion of tools with some excellant data and comparisons, photo's and drawings, all of which lead me to the case master. And of course there are better tools. And more tools!
And you are absolutely correct about averages and longer distances. Getting the loads and case prep conditions down to something that is repeatable is really the game. While 3 shot groups are sweet and a real confidence builder, 10 shot's or more at 200-300, IMHO will tell you more about the loading techniques and the tools being used and possible corrections that can be made.
I'm shooting hunting guns, and Handis at that, I am perfectly content with MOA at 200 and being able to hit a 8 1/2x11 sheet at 300 with the 708 an 308 (the 223 does much better). I seldom shoot at 100 any more cause it's kinda boring. The groups are too close to learn anything. Even getting a scope zero'd well at 100 is tuff. Too many clicks,,
I found that neck prep/case condition and seating was the biggest deal. Having the tool to measure, along with a few changes too and development of my techinques led me too that.
The path's that can be followed in reloading are many, as well as different guy's expectations and satisfaction of what "accurate" is. I have
seen guy's with scoped hunting guns walk away from the 100yrd range content with larger groups than I get with my .54 ML and open sights