On the subject of cartridge cases...
the kind of deep drawing of brass necessary to make cartridge cases larger than a pistol case wasn't possible at this time. It didn't truly become possible until the late 1800s, and even then balloon head cases, which are easier to draw than the solid head cases we have to day, stayed standard in commercial ammunition well into the 20th century.
Cartridge cases of the Civil War era, up through the early 1880s, were primarily drawn copper.
Copper is far softer and easier to work than brass, and it was possible to use it.
But, that comes at a price... Being far more maleable, copper "sticks" to the chamber a lot more tenaciously while there is pressure in the barrel, making a blowback weapon any larger than a .22 questionable at best.
And, because of the nature of copper, any amount of sticking in the chamber could very likely result in the extractor ripping the rimfire rim off the case, or pulling through the rim, leaving an empty case stuck in the chamber.
That very issue, stuck copper cases, was a big problem with the early Trapdoor rifles chambered in .50-70 and the early .45-70 rounds. The chamber would foul a bit, the case would become stuck, and the extractor would rip through.
"The gift which I am sending you is called a dog, and is in fact the most precious and valuable possession of mankind" -Theodorus Gaza
Baby Jesus cries when the fat redneck doesn't have military-grade firepower.