Officers'Wife said:
You are far more well versed in this subject than I but permit me to add this one observation. My uncle absolutely refused to reload 45-70 and it was the only cartridge he would use only factory loads in. His reasoning was that even though his Marlin could handle "hotter" loads should there be some kind of mix up on the range and my Grandfather try to use one of the "hot" loads in his "swing block" rifle the results would be disastrous. Said uncle worked with hazardous substances most of his adult life and never had an accident. I tend to respect his caution now.
With all due respect - it's really not that difficult, and it's easy to keep things straight. A responsible reloader will never have a problem with accidentally or negligently cross-loading hot loads in a non-compliant firearm.
Lots of very simple tricks which are very common for reloaders prevent this from happening, and of course, the responsible control of "if you're not sure, don't shoot it" takes care of all cross-loading issues.
A reloader can pick certain brass headstamps or colour (nickel vs. brass), certain bullets, or certain primer colours to uniquely identify either hot loads or light loads. If you use nickel brass for all of your light loads, then the rule is simple, never shoot a yellow brass cartridge in your trapdoor rifle. Or vice versa.
I personally use brass headstamp, and occasionally colour to demarcate my 45-70 loads. I do have cartridges where I know by the bullet which rifle it is to be used in and what the powder charge might be.
Keeping things well labeled and organized is the 2nd best line of defense (again, first rule is "don't shoot anything you're not sure about." Simply keeping things well labeled will eliminate a lot of headaches.
Then a guy can use specific COAL's so a few min and a pair of calipers will sort out a whole bin of cartridges.
And of course, there's always the option to disassemble a cartridge out of a group to identify the bullet, charge, and powder.
So personally, for my own 45-70, if I pick up a Hornady headstamp with an FTX bullet, it's a light SAAMI load, built to replicate the Leverevolution factory load. If I pick up the same bullet in Starline brass, it's a hot load only appropriate for my Marlin's and Encore pistol. If I pick up a cartridge with a lead flat point, I know it's a Cast Performance 405grn LFN-GC loaded over a Marlin only powder charge. If it's in nickel brass with a Nosler Ballistic Silver Tip, I know it's a SAAMI load OK for any rifle, if it's the same bullet in yellow brass, it's a hot load meant for my Encore pistol - just a touch lighter than max Marlin Only level.
Lots of tricks to prevent mix ups, even if the label happens to fall off of the box.