I have never send anything like this before. It measures 1" long and 9/16" diameter. It appears to have the word JAPAN stamped on the bottom. It seems to be lead....
It looks like it could be a pinfire casing. My brother in law has a pinfire pistol and pinfire ammo and it looks like that may be what you have. http://en.wikipedia.org/wiki/Pinfire_cartridge
If not a pinfire then probably not a casing. Most older casings had a rim(rimfire and centerfire) to properly space themselves in a chamber. look at a 30-30 case and a 22 case. most newer cases are rimless and center fire have a deeper groove for the ejector to engage and also have a round primer like a .308 03 a 30-06.