I've seen this episode only once, and it was probably about 25 years after it was made. I remembered Kurt Russell as being about 13 years old in the show, but the episode date would have made him 23. Whatever.
Anyway, Russell (the gunfighter's nephew) is chasing his murderer uncle around the country, comes into town and tells the bartender he is hunting Rance Woolf. The bartender says "A kid like you can't outfight a killer like Rance Woolfe", and Russell replies "I didn't come here to fight him. I came here to kill him".
As simple and straightforward as you can get. With all these Kung Fu movies where the bad guy spends what seems like hours "punishing" his foe (and then ends up finally getting killed when the good guy pulls a surprise move), that line was just plain fantastic.