Dear Justin,

Sounds like you've got one of these:

http://www.civilwarartillery.com/projectiles/spherical/IIIA4.htm

This is an artillery "shell" meaning there's something inside. If you can't see inside the shell it may still be filled with black powder which, as I understand it, can oxidize over time and is even more volatile than normal black powder.

You may not want to handle it until you talk to an expert.

Jim Martin in