Richard Fleischer's The Narrow Margin, although excellent at times, is not really a film noir. It's more of a thriller, with a hardboiled hero. But noir? No way. Charles McGraw is one of the most hardboiled guys ever (he would've made a great Mike Hammer) and his action throughout the film carries some noir overtones, but all in all the film's just a thriller.
At that it's great at times. Fleischer knows how to edit a fight scene and build up suspense. There's just one thing I don't get: there's this well-known gangster and his wife, and no one knows what the wife looks like! Was the guy ashamed of his wife and never went anywhere with her? (I remember liking Peter Hyams's new version of this in the early nineties, but I notice it's received quite a lot of negative reviews.)
Nicholas Ray's On Dangerous Ground on the other hand is truly noir, even though the ending is upbeat and optimistic. Well, it should be, since everything before it is gloomy and dark and pessimistic. Robert Ryan is great as the hard-hitting cop who's lost all his hope and just keeps on beating the baddies and snitches. Bernard Herrmann's music and the opening scenes reminded me strongly of Taxi Driver - and the both films share lots of issues about alienation and loneliness. Travis Bickle was in Vietnam, Ryan's character must've been in the WWII. (I liked Herrmann's music during the other parts as well.)
Yet the film is of great beauty. Some of the scenes carry the solemn grace of a silent film, of a Dreyer or a Sjostrom. I got into a debate with a friend of mine whether the ending was believable, but I said it doesn't matter when you're doing something this beautiful and touching. I found myself crying in the end.