Nice family heirloom. Many of these are tracked by the date code over the breech, which gives the year of manufacture. I assume yours is 41. The serial number of the weapon is also found in front of the trigger guard, as well as a letter suffix (when used). That would be the whole serial number, the one on the left of the breech is a partial and the rest are two-digit confirmations of original factory assembly. The serial on the magazine indicates it was issued to a pistol with that serial (4117) and there may also be a letter suffix there too, and if a plus sign is present, it indicates that the magazine was the spare issued with it.