Buongiorno, Marcello. Looks like you found another S&W gem in Italy! Your Model of 1917 is in great condition, but it does look like the stocks have been refinished. The plain American walnut stocks issued on most of the Model of 1917s during WWI were usually quite dark in color (see mine below, s/n 132922 ca. late 1918). I'm not sure about the concave circle at the top of the left stock, but it may have resulted whenever S&W decided to eliminate medallions on some of the stocks. I'm not sure what you mean by seeing these revolvers with "hollow grips"...if you mean inside the stocks, no. They were solid wood with no internal cutouts. Other than the light color of the stocks, your Model of 1917 appears to be totally correct with all the proper stamps. Congratulazioni, godere!