Who cares about 50 millonths??
You get that much change in dimensions after first shot, and powder warms up action..
100% Benchrest BS.
I can walk outside with a rifle part, and get a greater dimension shift almost any day of the year.
The cartridge brass expands/contracts even more with minor temp changes..
Headspace to .001 is nuts... I can get .005 just by walking outside at -40...
How repeatable is the 50 millionths rifle, when a cloud comes by and drops temp 10 degrees??
BS BS BS
Punching a nice small group of holes in a piece of paper, with a 110 year old rifle design, is well ..... boring....
The land of old farts petting their cats...
How about the real world... No sighter/fouling shots, no midrange wind flags, range not precisely measured, might have to shoot 3 times in a couple seconds.. maybe just iron sights...
Target might be trying to eat you... ( retired military here, target might be shooting back...)
That ultra precise action just jammed up by a piece of powder residue, or a leaf fragment, or a twig, or a tiny sliver of brass shaved off of a cartridge while feeding...