I'll take a stab at it. You
did ask what time it was, dincha?
Secifics is for your firearm & that one only - even consecutive serial numbers to be completely accurate but in tolerances probably not measurable.
Each firearm will require careful load development to reach maximum for that one specific firearm.
The "pressure ring" you mention, I'll take to be measuring the case head just prior to & again agter firing. Works to some extent, but mainly with never fired brass as each subsequent firing work hardens the brass causing less expansion.
For revolvers, sticky extraction can be a sign of over pressuring.
For any cartridge, very flattened primers is a sure sign you are getting into that grey zone. Note that primers flatten out as a normal result of firing, but should have a distinct radius from this (bolt face) flat towards their sides.
Pierced primers may be a result of a "defective" firing pin - one that's too sharp, but would be noticable on all loads. If you're seeing pierced primers (when not normal) you need to back off.
I'm with Art in that personally there's no sense in beating your firearms & you (at the added expense) of "magnun loads" unless required for a secific task.
If I've multiple shooters for any given caliber, I'll work up loads that work well in all of them.