See the numbers that I have circled in red down inside the loading gate? Not the numbers on the outside edge, but the ones down inside......
Those are factory bin (rework numbers). Gives evidence to the fact of going back to colt for rework. If you took the gun apart I believe you would see those same numbers stamped on every part (on barrel under housing, housing, front of cylinder, under grips on straps, bottom of frame, (perhaps the side of the hammer where you can't see it in the gun).
Click on image to enlarge.