Here are the proof marks. Photos are poor, so listed by barrel, starting nearest the breech.
Left barrel – ELG with crown (1893+)
Diamond with 16 over C (1898+); Perron; Star over V; ES - (provisional proof); Star over reversed P; CHOKE 16.2/15.8 (1910?); Star over S;
Further down
15.8; ES
Right Barrel
ELG w/ crown; Diamond 16/C; Perron; Star over V; Star over rev P; CHOKE 16.3;
Further down
15.8
ES
192
Forend hanger M4
Watertable has Perron, Star over V, An Oval with what May be JSD intertwined (Jannsen, Simonis, Doumoulin?)

I am including a photo of unusual engraving on rear of lock plates.

http://s916.photobucket.com/user/oldstarfire/media/IMG_1054_1_1.jpg.html

http://s916.photobucket.com/user/oldstarfire/media/IMG_1055_1_1.jpg.html

http://s916.photobucket.com/user/oldstarfire/media/IMG_1052_1_1.jpg.html