Sylvester Roper made an innovative revolving shotgun circa 1866-1870 which used a four round rotary “magazine” more or less like a sprocket arrangement to hold the cartridges in place. When the hammer was pulled back, it had a very long bolt type arrangement connected to the hammer nose, and as it was retracted it would extract a cartridge from the chamber of the barrel back on to the sprocket.
The hammer would then rotate the sprocket, aligning the next cartridge with the breech, insert it and a firing pin in the bolt would strike the percussion cap/primer at the base of the cartridge.
These were steel cartridges, closer to the early Gatling/Ager style steel chambers with a percussion nipple arrangement at the rear, and then loaded with powder and ball/shot from the front. Unlike the Gatlings, these had an extractor groove around the base.
I would like to make a few of the 16 GA. Roper cartridges to demonstrate the operation of a Roper shotgun (badly in need of restoration), but cannot find any details on the cartridges. I really need some good dimensions and photos or detailed drawings so my machinist can make some that will function mechanically. We will probably make some major difference in the internal details to prevent their being confused with originals.
Most of the Ropers were 16 GA, but some were 12 GA, and some .40 caliber rifles were also made. I am only looking for info on the 16GA.
Any help would be greatly appreciated. Also looking for details on the construction of the magazine internal parts.