The only way to ascertain the shipping date is a factory letter from Roy Jinks. It's only $30.
The WB on the butt is the Ordnance inspector's stamp - Waldomar Broberg.
The stamp on the underside of the barrel is most likely an import stamp - Navy Arms, probably.
JT
If the photo you mention is the one I'm thinking of, it's a British officer leading his men, and carrying an Enfield revolver.
Here's one from the Monte Cassino sector, New Zealand machine gunners armed with S&W .38-200s.
JT