In the early years of the transition from muzzle loaders to breech loaders, 12-bore brass cases for reloading were available.
Then, as factory-loaded ammunition in paper cases became more readily available, they seemed to fade out.
In the early 1960s, in the transition from paper to plastic, a North American company patented a case made of a zinc/aluminium alloy.
Its construction was very much like that of a plastic case, with a separate head and base wad, so it was clearly meant to be a ?throwaway? item, just the same as a paper or plastic case.
It wasn?t on the market for long.
I now see that all-brass cases, constructed like a rifle cartridge case, are available from a few suppliers in the USA.
They are advertised as being suitable for black powder reloading, and there are other snags. Being thinner in the wall than plastic or paper cases, they require oversize wads.
And, as they can?t be closed with a crimp or a rolled turnover, over-shot cards have to be fixed in with glue.
Oh, and they are designed for use with large pistol primers. There?s also no reloading data I can find.
It?s not that I?m trying to put you off, but with primed plastic cases costing about 13p each, and once-used fired cases costing nothing if you ask in the right places, it seems like a lot of hassle and expense for an uncertain reward!