Beagle, according to Colts layout and assembly manual, the bolt drop should occur a bolt width before the locking notch. It's inconsievable that a bolt could drop and fall into a perfectly fitted hole "on the move" as it would be. So, that's why the drop happens before the notch arrives. Colt (or his engineers) decided that the optimum point would be exactly before the notch and probably for the reasons you describe which are damaging the the notch itself.
So, as far as the Colt is concerned, the "Ideal" drop is ahead of the notch one bolt width.
The mark on the cylinder indicates that it is pretty close. The mark after the notch indicates a possible cracked or broken bolt spring or a weak or broken handspring. As Beagle333 says, an ill fitted bolt could be the culprit as well These could also be past problems that have been corrected.
The main thing is, there is or has been a problem with the action parts in this revolver. The good thing is , they or it can be/have been fixed. Changing a handspring or bolt spring is easy enough, fitting a bolt and timing it is a little more involved.
The articles that Fingers linked are very good and explain many things concerning these "un-finished" kits we enjoy so much.
Good luck.
Mike
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