Also, I'd be hesitant to believe that ANY guns built and proofed in St. Etienne were simply stuffed with a load of something, and marked as being proofed for something else, alá Two Piper's post.
Note Ted that I did not specifically say that St Ettienne did this. I simply said that many guns had been so proofed. This was a practise of highly respected proof houses having world wide recognition, though unfortunately I do not currently know just where to lay my hands on the particulars. You don't have to believe anything at all you don't want to, but truth is not really dependant upon your belief of it, now is it. The only point I was really making was it is not important what powder was used in proofing, only the pressures it was proofed for.
The use of black powder for smokeless proofing was merely cited as an example. Remember in these early days all shotgun propellents were quite similar in burning rates & all were rather fast & preceded the so-called "Progressive Powders" which would come later. Black Powder was a slower burning propellent than was any of the shotgun smokeless propellents of the day. A proof charge of it actually stressed the whole of the barrel "Except" the immediate chamber area more than did the smokeless charges. By the use of a heavy charge of very fine grained black it was possible to reach proper chamber pressures for an adequate proof for the smokeless & still also adequately proof the remainder of the barel for use of any charge normally placed within the gun.
I state this as "Fact", if you so desire do enough research to prove it "Wrong", but frankly I don't really care what you "Believe".
If the gun is designed to handle loads of 9k psi & a proof pressure of 12k, or 15k or what ever is desired it don't really matter if that ressure is reached by a load of black, semi-smokeless or smokeless, just as long as it is reached, is all I was really saying & the best way of assuring that is by relying on the proof house for the proper choice of a powder to accomplish their purpose.
