The Last Gun (1962) by Lee Floren

Jim Regan was scared, but not for his life. For his way of living. The West was changing rapidly, spurred by the invasion of twin ribbons of steel that brought a whole new population from the East and from the old countries across the great oceans. The railroads were opening the west, and men had to change with the time or die. Silver City was a town loaded with trouble, and Regan found himself smack in the middle of a shooting war with Apaches...and a personal war against a man who had sworn to see him dead!

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