Colt Lightning small frame question

[350mag1]

Hi all, I'm new to the forum and happy to see the amount of action here!!!! I purchased several guns from a collection and in there was a Colt Lightning. It has a round barrel and the only numbers I see are the serial # which is 1304. I do not see any markings of any kind on the barrel that shows calibre, the Colt name or anything. There seems to be a slight marking on the barrel but it's so faint that I can't even read it with magnifyng glass. It is registered as a Colt and has all the trates of the lightning. My question is: did all the Colt Lightnings have the name and other info stamped on the barrel? Thanks for any and all info! Doug