In that I have a 12ga percussion shotgun, I wondered how blackpowder would do in plastic cases. I have a good supply of once fired AA cases, so tried to develop loads. I also have odds-n-ends of various brands and granualtions of BP leftover from my BPCRS days, so I decided to use some of it up.
After a bit of experimentation I came up with 85gr volume 1997 vintage Elephant 3Fg, a .125" nitro card, lube cookie punched from a ribbon of extruded BP lube, an overshot card, 2 wraps around the inside of the case of printer paper (to keep the shot away from the barrel so as to prevent leading) 105gr volume of #6 magnum shot, another ocershot card, and then fold crimped. This left about 1/8"-3/16" of gap in the center of my crimp fold, but of no consequence with BP. For reference, this is at least 3 drams with 1-5/16oz weight shot.
These shot rather nice patterns from a full choke at 30 yards. With a modified choke the pattern was as tight, but would still easily take a turkey at that distance. There was less smoke than I was expecting. The test shotgun was a Remington Spartan SxS (Baikal).
A couple of damp patches down the tube followed by a dry patch and then WD-40 was all it took to clean up. I tossed the cases rather than cleaning and reloading them.
I also loaded up some 600gr slugs cast from a NEI .734-570 mould. They weigh heavier than listed with 25-1, but look like a big collar button. With Blue Dot recoil was ferocious
, and the fireball pretty large. I loaded 80gr, 90gr, and 100gr Goex 2Fg, followed by enough nitro cards and/or 1/8" felt Wonder Wads to get the slug set to the correct length for fold crimping.
My 20" Remington 870 with rifled barrel was the test mule. At 25 yards the 80gr load shot about a 2" hole at point of aim(barrel sights and no bags for rest). 90gr shot similarly, but 100gr shot a tighter group. I did remove the barrel and swabbed it clean between groups. The fouling came out with 2-3 damp patches, and no real leading was observed. The cases were tossed in the trash. Recoil is noticeable, but nothing like the Blue Dot loads.
I've since loaded more, but with 100gr, 110gr, and 120gr. The latter load is as much 2Fg I can get in the case with a .125" nitro card under the boolit and still get a correct fold crimp. These will be shot at 50 yards.