I'm no expert, but the OP's revolver is later than 1921.
The barrel ejector rod indicates it is 1927 at the earliest.
The S&W small logo on left side indicates 1937 at the latest.
If the stocks are original, the absence of medallions would put the date toward the early end of this range.
I'm not disparaging your gun. It's a really nice .32 HE. I would love to see more photos. I'm a great fan of the .32 HE and have two myself.
It looks like a very late 20s or early 30s production to me. Experts, correct me if I am wrong.
Curl