Help identify rim fire cartridge

[Jaybee]

I'm new to this forum and looking for help identifying an old brass rim fire cartridge. I found it with a metal detector in an old abandoned town site in Northern California. The cartridge appears to be .50 caliber, with a length of about 1 and 1/16th inches. The site dates back to the 1840's and was generally abandoned in the 1880's.211482 Thanks in advance for any help!

[Olut]

Without actually measuring it, it seems to be a .56-50 Spencer cartridge case

[merlin101]

To be sure we do need more accurate measurements as length, diameter at rim and above rim and at the neck.

[elk hunter]

Looks like the strike from a Spencer firing pin on the right edge. Also looks like a tooling mark on the base. Different company's used different tools to spin the case to spread the priming compound to the rim. Sometimes it is possible to tell which company manufactured/loaded the round from those marks. Most Spencer cartridges are so similar that it can be difficult to determine which caliber it is/was due to expansion of the fired case. Good measurements may solve the mystery.

[Jaybee]

I don't have a caliper or micrometer. Here's a picture or two with a scale. Base is about 5/8" diameter.211545211546