No, but as I said earlier, not all guns can safely shoot "published" maximum loads
So when there is a possibility of two or more maximum loads from any number of sources that's when the man in charge of loading the powder charge needs to be on full alert.
Yes straight bore (ie not bottlenecked) case / cannon barrel is more forgiving than one with a constriction, and BP is more forgiving than smokeless. But maximum loads are to be approached with great caution. Also maximum loads, while impressive, are hard on the equipment. No weapon wheather cannon or firearm, muzzleloader, or breechloader should be fired with only max loads. Over time these will cause damage to the equipment. Some of this damage can go undetected, until a rupture occurs.
Maybe I am overly cautious, but having seen rifles, shotguns, and one cannon barrel fail for other people. So I approach maximum loads with perhaps too much caution, if that's possible.