How to determine age of J.P. Sauer & Sohn SxS shotgun?

[martinwk]

I recently purchased a used J.P. Sauer & Sohn Royal 12 ga side by side shotgun.
On the barrel it says "Made in Western Germany" 12/70 2 3/4".
The serial number is B1123, numbers matching.
How can I determine the year of manufacture of this shotgun?

Regards,

martinwk

 

[VictoryXC]

There might be another three digit number stamped on it with the first digit representing the month and the next two the year. For example, 465 would be April 1965.