Some new details came in.
From mid February just before Colt acknowledge the issues on Feb. 21 Facebook & Youtube video.
"On January 1st, Colt had 2500 (so up to serial PY003500) 6" Pythons manufactured and ready to be distributed to dealers. As the issues (crowns, primer strikes and cylinder not rotating) were starting to show and calls to customer service began, Colt froze all further shipment until the problems could be corrected. Colt tested 16 guns at the range with the updates, if they performed correctly, which they did, they would repair the 60 guns that had been returned to the factory under the RMA system, that's why it took weeks for customers to get their revolvers back after the fix."
Some 4¼" were manufactured in mid to late January and shipped to dealers in the US before Colt started this process. That's why some 4¼" in the PY003800 range made it out with issues but some other, probably the ones still sitting at the distributor or waiting for export for us in Canada were updated with the latest fixes.