Range Report!!
I was able to pull the bullets out of a couple dozen cartridges and set the empty brass aside. Then took another couple dozen and cut the rim off, dumping the powder for some kind of later use. Was able to come up with a Rube Goldberg setup to push the bullets out of the shells. I will never in this lifetime attempt to do that again. Now I have empty primed brass and mostly good bullets. Powder time. According to all the old info I could find, each cartridge takes 4 magnificent grains of black powder. Right. Each shell took 2 grains with the bullet compressing the powder down. I used 3f on the first 14 rounds. I'll try 4f on the rest and see if I can get more volume.
Taking it all into the back yard, the black powder rounds all fired. I had loaded both with 7 rounds each and had no misfires. They worked, made a little noise and just a little puff of smoke.
Success!

Then I ran another 14 rounds (in each pistol) of the regular CB caps and they all worked like they were supposed to. The CB Caps felt like any 22 short pistol I have ever shot. The black powder rounds felt like shooting a cap gun.
My conclusion? With CB Caps it would be effective as a belly gun at very close range. Enough to let a person escape a dangerous situation. Maybe take down a squirrel or a rabbit if you could get close enough. The BP rounds? A slingshot or a pellet/BB gun would probably be more effective.
All in all, a most satisfying outcome. And now I have two more residents of my safe for my kids to sell off when I finally shuffle off this mortal coil.