As Rocky said they are very hard to find stuff for. The Brass Shells are available from CBC...Think you can buy them at Cabela's. I do have a few. I made my own wads in years past for the 410 cases I have. Mine also use small pistol primers. I used a .44 wad cutting punch and cut them from (if I remember correctly) either 36 ga or 28 ga cork wads. But you can cut them from any size wad. You just have to find the right wad column height...not too hard as you can put an overshot wad anywhere the load comes to up to a point. In my old brass cases I could use 24 ga wads in my 28 ga. and some16 wads in the 20's. As Rocky said the 12 required at least an 11 bore wad.
Rocky...as an aside in the distant past I even reloaded primers. Couldn't get shotshell but had some large(I think) pistol primers. Knocked the old primer out and inserted a new L pistol. Had to leave the anvil from the shotshell primer in place though. An old reloader from pre war times told me what to do. Worked fine but don't know the pressure things. Paper shells lasted just as long and shot fine. It was a bit tedious...but it allowed me to shoot when I couldn't get what I needed
