I found a brass cartridge case on a Union cavalry camp. it is bent and broken but appears to be about 50 caliber and 1 7/16 inches long. It is rimless with a small hole in the base and the base is flat. It is not a Gallagher. I'm not sure on the Maynard cartridge case, I know it had a wide rim. How was the rim attached to the body of the cartridge and could the rim be knocked off of the back of the case. If not this, does anyone have an idea as to what this cartridge case might be.