I am mainly a Smith and Wesson kind of guy but, couldn't resist this Colt at a gun show this last weekend. It is marked only on the six inch barrel as Officers Model 38 Heavy Barrel. Serial number 6186XX It has a 3/8 inch wide by 2 1/2 long front sight ramp that extends in the lettering on top of barrel. Has fully adjustable rear sight. Barrel cyclinder gap is almost non existant (no drag marks on cyclinder face). Grips have gold Colt Medallion. Gun is in excellent shape and I suspect that it will be a tackdriver. Is this someone's custom gun? How would I be able to tell if this gun has been to the Colt Custom Shop? If this gun is not original, the gunsmithing that was done to it is superb. Thanks for your help.