This Smith continues to be something of an enigma. I just noticed yesterday the mainspring tension screw head was ground down to blend in with the front strap. To make a long story short, it looks as if the gun may have at one time been a square butt changed to a round butt. If so, they did an exceptionally nice job of contouring the grip frame. This thing gets "curiouser and curiouser"! On the other hand, I installed an older sculpted hammer (post war) to go with an earlier look. (I know, it's still not correct, but it looks better than the semi-target version it had.) I put it in just to see how much fitting it would require, and presto, works perfectly, both single and double action! Even a blind squirrel............