Unfortunately it's a dead centre. I guess I'm just gonna have to lubricate the end I'm working on. But it pleases me at least I have one. ...if only I knew about it when I was running up those periscopes for my friends Seawolf!
(they ended up with fine lines down them. But my friend is still happy to have a set of pucker periscopes for his sub instead of just a piece of brass tube.