It is a .52-caliber Spencer cartridge, but the one in your first set of photos having a brass casing means it was manufactured after the civil war ended, because all which were made during the civil war had a copper casing.
Also, some of your first-set photos show a punch-mark a bit below the casing's upper rim. That punch-mark was a "stop" to prevent the lead bullet from getting pushed too far down into the casing. That wasn't done on Spencer cartridges until after the civil war's end.
The one shown in your second set of photos appears to have a copper casing, and no punch-mark is visible. If there is indeed no punch-mark anywhere on the copper one, it MIGHT be from the civil war era. That is why we do need precise caliper measuring (in 1/100ths-inch) of the diameter of the copper casing's top. All of the civil war Spencer casings measured .56-inch at the top of the casing. If yours is smaller (let's say .52-inch) it is from after the civil war.
Remember, no matter the casing top's diameter, if there is a punch-mark near the casing's top, it was made sometime after the civil war.
I do not see any kind of marking on the casing's flat base in any of your photos. By around 1885, most rimfire casings had a maker's-mark at that location. So, I would estimate the time range of your punch-marked but blank base casing(s) at sometime between the late-1860s to mid-1880s.
If have interest in learning more about Spencer cartridges, go here:
.56-56 Spencer - Wikipedia, the free encyclopedia
and here:
The American Civil War - Login
