"I Shot Jesse James"
Unlike many westerns of its time (it was released in 1949), it features a mix of character-driven drama and gunslinging action. It's a B-movie with a brain, and an exceptionally suspenseful and entertaining one at that.
The film is available on Criterion's excellent Eclipse collection - The First Films of Samuel Fuller, a series that releases overlooked films films from specific directors or themes. The people at Criterion have done a typically excellent job of restoring the film and transferring it to DVD. The set also comes with The Baron of Arizona (1950) and The Steel Helment (1951).