Leswad
As I said before your gun more and likely started life in the 30s as a double trigger plain extractor gun and was sent back to the factory in the 60s where the custom shop installed a complete forend with beavertail and a single trigger with new trigger plate which required a frame reblue.The custom shop would have done the engined turning at that time if requested.

Like I said, I did this to my gun in 1964.

You have a very nice gun.

AC