Complex sentence: Shooting Gus in his chest has little effect on him, and just as Gus is about to kill Chase with an electric drill, Chase retrieves his gun and shoots Gus through the head, killing him.
Split into simpler sentences: Shooting Gus in his chest has little effect on him. Just as Gus is about to kill Chase, Chase retrieves his gun and shoots Gus through the head, killing him.