Greg:
He could have easily been a supplier to Kaiser W. II and have been born in the latter part of the 19th century but I haven't seen any examples that were altered for Kaiser W. II's use. They could be out there but I just haven't seen them. Now he was just a purveyor/supplier to the Emperor & King and he rode that advertising wave to peddle arms to the general public. He may have just been the antler supplier to the Royal Court???? I haven't found where he was top gun retailer/gunmaker to the Emperor & King, just supplier. Say that the was a purveyor to thte court in 1905, then using the age of 24 years for his master brief and a couple years to get the appointment, then he would have been born in the 1870s, but for now I think earlier. I don't know when the appointments to the Royal court dwindled, but I would guess most were in the 19th century.
On the gun, I would want to see the proof marks. This looks to be a sourced longarm and I don't think Otto Bock touched it except for being a supplier. I doubt it was made in Berlin. How would it sit with you if it was a Sauer, or Belgian, with his name roll stamped?
Kind Regards,
Raimey
rse