I was thinking about what Drew is attempting to do, and I don't think a bit of boilerplate can be cleanly written that can be repeated all across the ether to useful effect.

I'd say something like, "If your gun was made before WWII, read the cartridge box, and use the lightest possible load you can make work (pressure and payload), so as to avoid injury, or premature decay of your firearm."
Then the SAAMI people could be pressured to make manufacturers print their pressures on their boxes. Like a cigarette package. Without the judgement.

Out there doing it best I can.