at first glance, the grips look like 1920's vintage but they are not serially marked and the upper portion is both concave and lacking any shield
The frame is round butt but somebody wanted the full profile grips and made walnut spacers fore and aft to fit square butt grips. The serial number is 602,000s. Supica and Nahas don't provide much information but one reference said that McGivern shot some sort of record in 1934 with one of these in the 640,000 range. The elevation adjustmentis counter intuitive - reverse thread or something- like persisted on the windage adjustment on later S&W sights.