I love the little snubbie!!!
A few observations to add to the great info given by Jack, Mike and others above (I know that both Jack and Mike have spent years studying the K-frame M&Ps and I always appreciate their comments and wisdom). Personal observations:
1. The rebound spring stud protruded (a domed bump) on the left side of the frame (just above the grip) on the pre-war guns. On the post-war guns that stud was ground/buffed flush with the side of the frame, which is how the left frame looks on this gun, indicating that it was "finished" after the war.
2. The finish looks to be the post war blue (more of matte finish) also indicating that it was "completed" and shipped after the war.
So I am firmly in the "pre-war parts, post-war shipped" camp.
And I look forward to seeing what the letter details.
Just a note of caution on the rebound stud - on most refinished pre-war guns this stud is also polished flat on the left side, indicating a refinish... I do not believe that this gun was refinished.