Howdy Mastadon,
After reading about one in a 1971 blackpowder book, I bought the first one I saw. It is the ONLY one that I have ever seen. The little thing is like new and as cute as a button. They are about the size of the "Cricket" 22 rifle. There is a little twist breach that you rotate 90 degrees and dump in 5-7 grains of FFF and push in a .24 ball (I have to use pliers with leather on the jaws). Remove the cap holder on the other side of the breach and put in a cap, they use a cap like used in a cap pistol. Rotate the breach back to line up with the barrel and shoot. The caps are the problem, when the gun was made, the caps had more powder in them. The new ones don't have much and you have to use two to get them to fire. I don't know how to post a picture or I would.
Lee