Again my apologies for not responding sooner, but without an email notice, I tend to forget. I'll try to do better in the future.
Anyway, here are some pictures of my Collath. Since the chambering was something of a mystery, I decided I needed to completely disassemble it, and "get to know it". I'm certainly glad I did. I love this piece.
This is a collage of the area around the action:
Here are some of the action partially disassembled. It is a beautiful example of simplicity and workmanship:
Here are the sights:
Here is the cartridge I finally settled on:
And here is a slug of the bore and a scaled drawing of the rifling. Collath was quite the "independent" thinker.
Paul