I don't know offhand when Ben Lane was engraving for Colt. The books I have are not clear on that.
Jan Gwinnell was another Colt engraver. I have one by him that was shipped in 1986. JG could be mistaken for JC, I suppose; however, my Jan Gwinnell engraved gun is signed with his full last name under the grips on the left side of the trigger guard at the bottom.
TriggerTripper - I am curious how you know that the grip frame is stamped "JC" if you are not willing to take the grips off. When I get a Colt with factory engraving, the first thing I do is to take the grips off to see if there are any stampings on the trigger guard/back strap (serial numbers and/or engraver's name) and, if the gun has ivory grips, to treat the ivories with mineral oil.
Second generation factory engraved Single Action Army revolvers were almost never signed by the engraver. Exceptions might be some of those engraved by William Mains who used a small "buffalo" figure on his guns. A factory Master engraved 3rd gen Single Action Army will usually, but not always, be signed under the grips and Archive letters on such guns will usually, but not always, name the engraver. Expert and lower level engraved guns will be marked "COLT ENG" on the left side of the trigger guard at the bottom, are not signed and not usually named in an Archive letter.
- - Bruce in Ohio