The reason I have nasty suspicions of the person who marked that slide with the "Colt 9m/m" is that (IMHO) it was done for the purpose of deception.
That's usually the case. I'm (very) ashamed to say I got burned once on a very clever faked pistol that I got from a supposedly very reputable collector.
Anyway, I really appreciate all you guys' insghts into this item. At least now I don't have to sit here and scratch my head and wonder. LOL!