Well of course it really does't make any difference what powder is used for the proof. The proof house picks powders suitable for their purpose. "MANY" guns have been proofed over the years totally with black powder & marked with a "SMOKELESS" proof. This was quite often accomplished by giving the gun the regular "Black Powder" proof with a coarse grain BP to insure the major portion of the bbl was adequately proofed while an auxillary proof was fired with a Fine grained BP giving ample chamber pressure to insure it was safe to use with the normal smokeless powders for the chambered cartridge.
The important point is not what it was proofed "With" but what it was proofed "For".

Miller/TN
I Didn't Say Everything I Said, Yogi Berra