Gun Cotton Crate?

[kaskowiski]

This item came from a military site dating back to the 1880s where gun cotton was used in large quantities.
My best guess to date is that it was a plug in the lid of a wooden gun cotton crate. The plug appears to have a tapered pipe thread. The outer flange measures 2 1/2 inches diameter and the plug is 1 1/8 diameter. Both the plug and flange have RL and broad arrow stamps.
Has anyone seen anything like this before. Any suggestions most appreciated.
Kume

 

[Gspragge]

Guncotton had to be kept wet so there would have been a metal container of some sort wether this is from one or not I don't know.

 

[kaskowiski]

I have checked the Treatise on Ammunition 1877 & 1902 and they clearly describe a G.S. screw plug in the lid of wooden gun cotton cases. I just cant find an illustration to confirm my theory 100%.