Python chamber edge wear marks-cause?

[skeeter]

I noticed on 3 chamber edges there are SLIGHT wear marks (like rubbed by a dull knife) where the blueing is worn away. Also the hand at one corner has a wear mark (shiney area) and is not an 90 degree edge. All other Pythons I have seen do not have this. This is the Python that sometimes after being fired you will not be able to cock the hammer back for the next shot as it jams about 1/4" back. It will not always do this. Is it possible that the force of recoil is bouncing the hand forward into the chamber edge and the force of trying to cock the hammer when it does not want to be cocked is making this wear?
Also, when I got the Python I checked the timing by pulling back the hammer 6 times to see if the bolt locked in place when the hammer was back. All looked OK but before I sent it back to Colt I was cleaning the cylinder by holding a oiled rag against it as I rotated the cylinder by cocking the hammer. I noticed that after the hammer was cocked 3 chambers would not allow the bolt to engage the notch. As I rotated the cylinder by hand I could then hear the bolt click into the notch.
Could the drag of the rag prevented the momentum of the cylinder from moving forward to engage the bolt and without that drag I got the false impression the timing was OK because of the cylinder's momentum. I was not really pulling the hammer back as slowly as I should have?
Any thoughts on these two issues?
Have any of the smiths here seen these chamber edge wear patterns before?

 

[govmule84]

I'll play...

...I am not an expert, and one of the more senior members may be along to correct me, but if those drag marks are on the front of the cylinder, it sounds to me like you could either have a slightly bent crane, or, more likely, a cylinder that has a little too much endshake.

If it's the endshake issue, I believe installing washers is not too difficult on a Colt (it's cake on a Ruger, that much I know.) If it is a bent crane, I think it is gonna go back to Colt.

 

[Scorch]

Dragging the cylinder is not a reliable test of timing on a Colt, but it can point out if there are possible issues. Due to the way that Colt revolvers time, the cylinder does not have to lock until the trigger is pulled. Pulling the trigger pushes the hand against the ratchet, rotating the cyinder and holding the bolt stop notch against the bolt to ensure complete alignment of the chamber and the bore. There has to be some play in the trigger mechanism of a Colt revolver to allow the nose of the trigger to clear the hammer sear when the trigger is pulled, but that play should be just enough to allow this clearance. However, even seemingly minor wear on the hand or bolt can significantly affect the timing. Contrast this with the way S&W or Ruger revolvers time (i.e. on the side of the pad), and a lot of people get all worked up over nothing when they feel the Colt is not completely locking.