I figure I already know the answer, but will ask regardless. I have recently seen a Colt 1911 with Colt and U S Property marks, etc intact, though rearsenaled. The serial number is not the usual stamped variety, shows signs of having been ground off, and a different serial number engraved in its place. The engraving is deep and nicely done. One person in the group thought damaged pistols might have received this treatment. I recall no such practice being mentioned in my limited U.S. pistol experience. What is the scoop on this piece.