I recently purchased a Colt 1917 revolver, straying from my usual purchases of familiar S&W revolvers. I got this Colt for a REALLY low price as the finish looked as though it was placed in a case tumbler for about half a day. I really didn't mind that. However... Looking over it carefully, I was in horror to find that every external surface was taken down to the point that the hammer stud was ground flush with the body of the frame! EVERYTHING was SO smooth... the barrel had a few marks left, the side plate rampant colt was LONG gone, as was every other mark on the gun except for the serial number. I then noticed that even though the Colt displayed the "bank vault" lockup AND it worked flawlessly in single action mode, in double action, it displayed cylinder "throw-by" in half the chambers. I am obtaining a new cylinder because I am sure this is part of my problem. My question is however: What causes this condition on the old style Colts, wear? abuse? home gunsmiths? I would like to put this old girl back in SAFE firing condition but don't want to spend a crazy amount doing it.
Any suggestions??

Probably needs the cylinder-bolt adjusted if it's carrying over

This particular gun seems to have been used and abused a lot, but in general, Colt's cylinder timing wears a LOT faster than Smith's. I've never personally seen a Ruger DA that was out-of-time.

Most older Colts that I've handled were out-of-time and a very famous pistolsmith told a friend of mine that he could re-time his Python, but it'd probably be OOT within 500-1,000 rounds.

I quit buying Colt revolvers a long time ago and this was the primary reason why.

The MK III and later guns don't have that issue, but have others, so I never warmed to them .

S&W's N-framed .38 and .357 guns also wear the timing sooner than do L and K-framed .357's because the big, heavy cylinder wears the hand sooner. But they're still a lot better than Colts in that regard.