Dave
Got some thoughts here, but this is an odd pup. I've got to base my thoughts here on the pistols I have seen that were definitely 95%+ original. This one does not comply with others I have examined. It looks like an old re-stock, but I believe this original set of parts is on a stock possibly done in the 1950's or 60's+. The rod appears older than the stock but that may be because of the use. The parts appear are legitimate. As for the marks on the mainspring the comments may be right, but in all my research, I have never seen the marks turn out to be right in the bend before. May be I just haven't seen enough, but I have physically examined over 1610 now, so I do have something to base that comment on. Normally, these are makers and assembly marks; which may or may not be the same. If you take the lock apart, you should find marks which will/should match in number and style to marks on the plate, bridle, sear, sometimes the sear spring, frizzen, hammer and on occasion, the tumbler (but get out your magnifiers!).
If you find a difference in the marks, it is a repair; no argument, and common to replaced parts on a well used arm. I would guess this to be a restocked arm by a contemporary maker who had adequate skills, but not exceptional. That would explain its unusual shapes and contours different to original pieces, even cheaper trade arms.
Susie