Looks a lot like O. mykiss to me. Even if it has some sort of color under the jaw, this is seen in some redband rainbow. With all the moving around of rainbow stocks it is easy to see how some might get mixed in. Only way to know is with the genetics.

In the last few years I have seen photos of whay looked like "pure" cutt or 'bow. Genetics said otherwise. Said they were the other species, and pure, at that.

As to the long maxillary (upper jaw), I have see adult rainbow with prettty long max's. That character, in my experiance, seems to work best on smaller (8" or less) fish.