The grips cover the butt have to take off to see numbers so they are not stock grips? They were wood grips like I see on others?
I would say 75/25 that the gun originally had grips like this one:
This is a 32 hand ejector third model so it is later BUT generally ALL of the round butt guns in those days had the hard rubber grips. The wooden round butt grips were earlier (model 1899 K frames for example) AND later (post war). For these I frames, I'm almost sure that all of the pre war round butts would have had hard rubber UNLESS special order. If the gun was special ordered with those extension grips, IMO the SN would be in the SAME place it is now.