Can anyone ID this hollow brass tube?

[GopherDaGold]

This brass tube was found by a friend in Missouri near an area that's provided a lot of Civil War bullets. It's hollow but has some corroded material lining the inside. The two nubs on the side are a mystery as to their purpose. The top edge looks like it might have been cut or broken because the edge is a little rough and uneven. Anyone have any ideas what this object was?

 

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[KeyaPaha]

Brass ferrule for joining sections together on old cane poles.

 

[GopherDaGold]

Brass ferrule for joining sections together on old cane poles.

I like that idea. Thanks!