Hey guys, and Victor3 you'll get this, I found out what I was looking for. When I ask "Is there an old timer's formula" or a "General formula" for figuring out your powder charge assuming that you have a good quality piece? All I got was "Go to the safety load sheet" which as I recall topped out at around 150 grains of powder (correct me if I'm wrong, but that's what I generally remember). The answer to both is a "Square Charge" of powder. Simple and easy to figure out and yes, the old timers used it to figure out their charge of powder.
All it is, is to take the diameter of the bore (say 1") and get a cylinder of that very same diameter cut to exactly that same length. So in this case it'd be a 1" diameter cylinder exactly 1" long. The powder contained in that cylinder would be the charge you'd go with, simple.
I now have three big massive hunks of stainless. One turned into a BNA Eprovette Mortar, and two milled into a 1" bored double shot and a triple shot signal devices. I asked really for the 1" jobs as my BNA came with a powder scoop. Well when answers weren't forthcoming I decided to check a few things on my own. In the process of that I noticed a soap companies line cast into what I was using as a powder measure for my BNA mortar. Concerned that I may be using too much powder (full cup or just to the line?) I wrote the manufacturer to find out. He's the one that told me about the Square Charge and the laundry scoop was indeed that, a square charge for my mortar. In other words, I was supposed to fill the cup up to the top.
Now comes the fun part. The soap company's molded in line (I know, I don't use that as a reference) contains 600 grains of powder. Now the exciting part, the full cup (the square charge I'm supposed to use) contains 1200 grains of powder. Go figure. I never found a 1200 grain suggestion of the safety list I was always being referred to? Why is that? Full sized cannons have to be using powder measured in pounds not grains otherwise the ball would not shoot and may stick in the barrel.
Now back to my 1" double and triple units. A square charge for them would be the above mentioned 1" cylinder and 1" long. I haven't checked it out yet, but I'm guessing that a square charge for that will be in the neighborhood of 600-700 grains, maybe more?
Now admittingly my latest purchase, 1.7" bore X 10" length which was supposed to look like a cannon barrel ended up being a piece of high pressure stainless pipe with a breech plug welded in. The square charge for this would also be 1200 grains of powder due to its bore, but I'm a bit leery of testing that theory. Maybe I'll just put 200 or so grains of powder in it, a wad and some confetti?
I am having a Thunder Mug made of stainless and it will be built like my BNA mortar was and my 1" signal guns. 4" of stainless at the base tapered down to just under 3" at the muzzle and bored to golf ball size, actually a bit bigger since it will be 1.75". It will certainly hold and handle 1200 grains with no problem whatsoever. After all, all I'll ever be shooting is a piece of cardboard with a circle of 3X5 card stock for a seal, out of it. Figuring that out of my eight bores (5 1" and 3 golf ball) only one is not permanently built to shoot straight up. The one is set permanently at a 45. I can't really run that fast to avoid 7 golf balls and 1" balls coming back to earth.
So a very simple and quick answer to my questions here would have been "A Square Charge of powder which is bore cylinder by diameter length" Simple. Smithy.