Let's just cut down to the bottom line here, there are any number of "Smokeless Powder Proofs" applied to guns of various proof houses, some naming the powder, some not. "MANY, MANY" of these proofs are not considered adequate for modern day SAAMI spec (ala Wallie World) shells. If the proof load was such that the gun was considered proofed for say a 9K psi load, then if your load does not exceed that 9K psi, then it doesn't matter if it was proofed with, or if you are loading; Black, Poudre M/T, Shultz, EC, Mullerite or " DuCules Purple Polka Dot".
The two points of importance are to what pressure level was it proofed to handle & what pressure level are you shooting. Now that doesn't seem too hard for a person of reasonable intelligence to understand.
It is not necessary that we be able to obtain the powder these old guns we talk about here were proofed with in order to obtain a load we can safely fire from them. Very fortunate, otherwise they would all be WallHangers.
