What is it? 20MM gauge?

Here is #2 for the day for the ordnance experts. What is it? Pic attached.

It looks like rather "rough turning" to me, compared to how I would turn metal in a lathe.

First impression is it's a shop project.

Flying10uk and Aragorn243,
Many thanks for your observations. Upon closer examination I agree it is most likely a shop project. What I thought was a much used tool/gauge is a poorly turned piece that is not concentric in one step to the next. Many Thanks, Steve