Beautiful pair of guns. The Rasch double rifle was built between 1892 and 1912 by the style of the proof marks, and with the gauge mark of 108/49 (.350") and 3,59 grams of powder it is *probably* a 9,3x74R - only a chamber cast can tell you for certain, though.
You can see a good basic discussion of German proof marks at:
http://germanguns.com/technical.html Kersten's Verschluss (bolting method) refers to the two upper barrel extensions into the breech face secured by a transverse locking bar. Flussstahl indicates fluid steel, rather than Damascus or laminated, and the barrel steel came from the Krupp works in Essen, Germany.
