Dave

The white-outline cut into the face of the rear sight is proof enough that the gun was modified by King. That modification is called a low-light rear sight. Check the front sight blade carefully, to see if the King name is stamped anywhere on the blade. That would not confirm that it was a King modification, as anyone could have done that. It's also not known just how the gun was configured when it left the S&W factory.

However, it certainly is possible/likely that when King modified the rear sight, he might also have milled the front sight to accept a blade, and then mounted a King blade. We'd have to look through the King manual, and see if he made a front sight blade shaped like the one that you have.

You might also check the action/lockwork, to see if the hammer throw was converted to short-throw. You can tell by simply pulling the hammer into single action lock.

The tang of the hammer was either broken and then repaired, or was modified, or possibly even replaced. You can look carefully at the sides, and see if the King name is stamped anywhere.

As it stands now, the only connection to King is the modified rear sight.

Regards, Mike Priwer