Here is a 20 Gauge /.65 Ballard new primed empty rimfire shotgun shell. The only information I can find on it are a couple of descriptions from Buttweiler Auction catalogs. He started it was for a short lived Ballard combination rimfire/percussion shotgun from the 1860’s. The fired rimfire case could be fitted with a percussion nipple and fired in the same gun as a percussion cartridge.
Rim: .578” (19.25mm)
Base: 0.663” (16.84mm)
Neck: 0.663” (16.83mm)
Case length: 2.28” (57.97mm)
Does any have a pictures, drawings or other information on this cartridge and gun? Any idea of who manufactured the cartridges (CTM?)?