Hi, I own the 23aa Model which was made between 1933 to @1940, As far as I know the triggers were all single stage triggers, One spring can be changed to lighten the pull. I have a Model 15 Savage made aperture sight on the rear and a Lyman 17 Globe for the front sight.
Action cocks on opening vs the 23a that cocks on close.
Walnut Stock has checkering at the grip and under the forearm, Believe it's the deluxe model as most had plain stocks.