Agree with Lagopus that it looks like a Grade 3 Model 400. Very popular gun, and the direct predecessor of the 700. W&S went backwards on their grades on the 400's: 3 was the basic gun, 1 was the highest grade. They got even more confusing with the 700 series: 700, basic gun; 702, next step up in quality; 701, top quality of the 700 series.