That was a great gift,
@Rod Man ! Nicely documented, too.
I've heard of King's Semi-Smokeless, but have never used it. I'm not really sure what it was, but I have seen it referenced in the old blackpowder literature and people did use it in their muzzle loaders. I have a little handbook my dad gave me many years ago, entitled
For Beginners Only, written by B.M. Baxter and published in 1949 by the NMLRA. The author has this to say about King's powder: "
King's Semi-smokeless powder is preferred by many but is off the market at present [1949],
still some might be found in stock. King's 'Semi' is usually recommended in grain one grade coarser than black powder" (pp. 39-40). Baxter did later go on to say, in all capitals, "
DON'T USE SMOKELESS POWDER OF ANY KIND IN YOUR MUZZLELOADER...", so he was certainly aware of the issues. This leads me to believe the "Semi-Smokeless" name may have been a marketing ploy, and the actual propellant was likely just some form of black powder. We wonder if it might have been a precursor to today's black powder substitutes, e.g. Pyrodex or Triple Seven. I don't know that... I'm just speculating here. Walter Cline described using King's Semi-Smokeless in his book,
The Muzzle Loading Rifle, Then and Now, and in fact Ned Roberts mentioned it in his book, on the page right after the one shown in the photo. Roberts didn't like it, and he appeared to think it had different burning characteristics from the other black powders.
Any of those cans would have been nice for a collection, but I would say you picked the right one!
Best regards,
Notchy Bob