I have a tendency to agree - a sanded type 5. The second and third picture shows how it was originally coming off the nose at one angle (original potbelly) and then abruptly changing the angle to become flat. There is also an inconsistant "bump" in the middle of the trigger well and mag well - this is the location where the "potbelly" starts bending down to become fat.

Of course, I fully expect my observations to be discounted and proven wrong.

Where is Painter when you need him????

Frank, are you around?