[wterrell]

"This isn't a terribly complex operation and could be accomplished quickly"
This operation would be totally unnecessary. The barrels would have been threaded and timed using a 'dog' to position the mount of the front sight. They would then have been torqued to the frame and the dovetail cut for the front blade. And then the barrel would have been struck with the witness mark.
Cheap, logical process, with no unnecessary operations.

"Viggo stated to indicate that a part had been removed and/or if the part is removed to assure that it is reinstalled in proper alignment"
This is the purpose of witness marks.