The stepped water table is the key.
"Stepped water table" is actually a beautiful translation of yours, much better chosen indeed than the original (and stupid) German term "Nasenverschluss". 🫡👍
While the engineering expression "Nase" does of course have a due place in gunsmithing lingo, exempli gratia for a rising bit (rising stud), it is very much inadequate for describing this (simple but charming) contraption, which in the 2020s fad jargon would probably be called a "hack".
In proper German for engineering and patent-applications (which T&S did not care to use), one could call it maybe "Verschlussabstützung durch Stufe", or looser and a bit more imprecise, "Falz".
Regards, Carcano
