I will not be much help here as this is not my forte.
Back when Hans and i were researching the man, by me, and the guns by him, he noted that there was evidence that the Ritz Bros. should be included.
If memory holds, Hans had a Lindner Daly 12 gauge with a tiny mark in the action that he attributed to Ritz Bros.
Don't know about the tubes, though.
Unless I am in left field, the Schilling barrels should be marked with the S in a six sided cartouche.
Best,
John

Humble member of the League of Extraodinary Gentlemen (LEG). Joined 14 March, 2006. Member #1.