Proofs:
Post 1892 marks for Imperial Germany
"Crown over S" - smoothbore mark, "Crown over W"- choke barrel mark, "Crown over U" - Üntersuchungsstempel -final definitive proof, "Imperial Eagle"- preliminary proof , 12 in a circle is gauge of chamber and nominal bore, 13/1 is actual bore size, small multiple lobed crown is the perhaps the earlier Prussian crown although I am not sure, the larger crown is ( I believe) the Prussian State Crown.
I suspect the gun was not proofed after 1912, as the crown marks arent usually seen that late. If that ius the case 9 and I could be wrong, the chamber length is indeterminate. Any gun proved after 1912 should have "70" for 2-3/4" chambers, and absence of the number indicated 2-1/2" chamber.
Somewhere you might also find a proof date mark- three digits indicating month and year of proof.
The gun should work fine with normal CIP 65 mm loads, but bear in mind that after close to a century of use, 7500 psi loads might be kinder.
Regards
GKT
