Ed - I cannot match it to anything in 1922 catalog I have. My gun's SN started with a D and had 4 digits. I am fairly certain it was made in the 1950s, so that SN does not give much guidance on the DOM for this gun. I believe the double proofmarks indicate a "heavy" proof, which seems odd in light of the 2.5" chambers.

Such a long, long time to be gone, and a short time to be there.