Again, one more time, I have a rifle that shoots one hole groups, I had another rifle that shoot patterns (like a shot gun), the rifle that shot patterns was a Winchester Model 70 chambered to 300 Win Mag, I shot the same ammo in both rifles, one more time, one shot one hole groups, the Winchester shot patterns,
I am really trying to understand the point you are trying to make....
You have a rifle that shoots birdshot groups, and another, of a different make, shoots one hole? And you automatically attribute it the chamber/case length? I must be missing your point, because it could be innumerable other things including those as obvious as a crap barrel, or out-of-true action... or that rifle just doesn't like that ammo. Are you saying that all rifles should shoot the same ammo with identical accuracy? We all know chambers vary, and are still within SAAMI specs. So?
Many long-range precision shooter use a chamber gauge in the interest of not trimming their brass until it is necessary
. Why trim brass if you've still got throat clearance, regardless of SAAMI spec.
Please re-state your point more clearly for me if you don't mind...guess I'm having a senior moment (pre-senior)....