From this photo, the mark the receiver was applied before the bluing, and the mark on the barrel is after the bluing, which makes lots of sense to me -- one of them had to be fixed to align the other one (floating one) to it. From what I read in the past, was the theory saying both were floating (i.e. both applied as the result of a single 'blow').... I had hard time to make sense out of single blow theory.
Edit: Most important, it looks good to me
