[Sopater]

Had Mr. Gaskill not confronted Rollins, the shooting would most likely have continued.

Exactly right. A good-guy with a gun doesn't necessarily have to actually shoot the bad-guy to stop him. Often times, just showing up and presenting the willingness and capability to use deadly force is enough to end it.

[Heart of Georgia]

“A good-guy with a gun doesn’t necessarily have to actually shoot the bad-guy to stop him”

Same scenario happened at a local Home Depot. A young man showed up there and shot his former girlfriend and another person. He then left the store and was confronted by an officer who was right out front, and shots were exchanged. So having no way out, he went back inside the HD and shot himself. If the officer hadn’t confronted him, the murderer would have gotten away.