Found this rim fire casing and think it is civil war. It appears to be cooper and has hammer mark on rim. The rim mikes at .640. The casing is somewhat deformed and best we can get is .600. Cant get a length. thanks
It appears to be a fired .52 Spencer Rifle/Carbine ".56-56" cartridge-casing. The base-rim of that type was .645" in diameter, and its unfired body was .56" in diameter. The Spencer casing's nomenclature was different from that of every other type of cartridge-casing... its caliber was not represented in its nomenclature, only its body-measurement just above its base-rim, and the measurement at its top. .56-56 Spencer - Wikipedia, the free encyclopedia
Because the top of your Spencer casing is broken off, there's no way to know whether it is a civil war .56-56 or a strictly-postwar .56-52, or .56-50, or other after-the-war-ended version. Very large numbers of armed yankee troops occupied the defeated South from 1866 through most of the 1870s, and they used postwar versions of the Spencer cartridge. That being said, if you found it at a spot whether other civil war era firearms projectiles have been found, its more likely to be the war-years version.
One of the photos below shows an excavated civil war era .52-caliber Spencer .56-56 cartridge, and the other photo shows two non-excavated postwar .50-caliber Spencer .56-50 cartridges.
Here's a .56-56 I found a while back at a Civil War-era site in TX... Apparently out of the couple dozen I've found, I only have photos of one on my phone, haha.