Utilitarian Barrel Key Help

[Tumi]

First, thanks for your time. I've been to a couple of antique stores around town and haven't been able to get any information. I figured I'd take this to the experts.

I live in Atlanta, Ga and found this key in the yard. There's a lot of History in this city so I'm thinking it's pretty old.

I think the key is bronze or brass. It has a utilitarian clover-shaped bow. It looks like it was made hastily (there are a lot of file marks around the perimeter of the bow and shaft). The ring hole is not centered. It has 405 stamped on one side of the bow (they didn't take the time to strike it very well), otherwise there are no markings. It's almost 3.5 inches.

I'm glad I found it and love having it around. I just wish I could put a story behind it because it looks so interesting. Any information would be appreciated. Thanks!

*History of the area* There are a lot of trains and tracks in my neighborhood. There is also an old Civil War fort about a mile away from my house.