The Rifleman S2 E02 Bloodlines

The three Malakie boys comes to town and bust up the saloon. Lucas McCain and Marshal Micah Torrance stop them, but in the course of doing so, one of the boys shoots and kills his own brother. That doesnt stop them from blaming Lucas however and when their father Daniel Malakie arrives, he breaks his two surviving sons out of jail intent on getting even. They ambush someone they think is Lucas but get it wrong and Lucas and Micah hunt them down.