Steve,
Your description of the color reminds me of a case cleaner in use in the 60sand 70s, but it would go away with use and polishing. The lack of headstamps could mean he bought a large quantity of basic cases( such as 9.3x74R) from some manufacturer and made all his rimmed ammo from it. No headstanps would be both cheaper and less confusing. If so, his source would be known only to him. When I make .310 cadet and 8.15x46R cases, I thin the rims from the back; a surprisingly small amount of thinning removes the headstamps. Maybe he used a different caliber case and thinned the rims. It was common to use 30-40 Krag cases, in spite of smaller headsize. This would show up with expansion ahead of the web. Lathe turned cases color could be yellow if turned from brass. Such cases could be identified by inspecting the inside of the case, and would be expensive.
Of course both of us know the above is pure speculation as I have never seen the cases.
Mike