WA, As far as I know, there is no data. I simply used a fast shotgun powder,(AA nitro 100), then guessed at an appropriate charge. I figured with the size of the combustion chamber I could go with around 20.0 grains behind 1 1/8 ounce of shot. That would be a stout field load in an AA shell. It was so mild it wouldn't function the action in my beretta 390. It barely moved the bolt! It was very slow as well and the pattern was lousy.
The inside diameter of the case is
MUCH bigger than that of a plastic shell. For that reason you cannot use a standard 12 guage wad,(one piece or plastic gas seal). I'm using 10 guage over powder card wads,(paper). They fit nice and tight. Also the lack of a base wad means you have a
LOT of room to take up. I use 12 guage fiber wads to create a wad column, then a 10 guage nitro card wad for an under shot wad. Topped with a 10 guage thin over shot wad, then sealed with a latex sealer.
Because of the large ID of the brass shells, I doubt they would be good for slugs. The 12 guage slug would have a lot of room around it's OD, it would rattle around in the case. Then being fired off-center wouldn't do much good for it's accuracy.
Same goes for the buckshot. It would be loose in the shell, then have to be squeezed into the 12 guage barrel. Not good for a pressure spike right at the mouth of the chamber.
So why do I have them? Good question, 'cause they look neat? 'Cause I like to be different? I've been loading just about everything I could get my hands on for over 40 years. I get bored.
Something new to work on, a new project!
I WILL make them work! I'm aiming for a target load using smokeless powder, 7.5 or 8's, at 1200 fps, with a pattern that will break some clays. Not sure if I'll stick with my O/U or try to get them to work in my 390.