On my example pic. the serial number is 16020.
The proof number 1779 indicates that was the number proofed (1778 proofed beforehand) and the dot22 is the year of proof.
Cannot be certain what to make of it if there's no dot followed by a number.
Others on here may know better than myself. However a good pic of both sides of the barrel/receiver may help more.

My rifle has the word Nitroproved on plus NP with a small V under the P