Originally Posted by ellenbr
So Greener's contribution to a tube extension lockup is a single extension with a circular or square hole anywhere along the interface of the action - tubeset?

That's how we see it in Central Europe.

P.S.: Central Europe extends to Lemberg and Czernowitz in the Southeast, and Reval in the Northeast (plus many manor houses).
That's about the maximum extent. (Ultra sunt leones...)

Carcano