What about shooting one of those shotgun shells designed to be a noisemaker?
Another warning shot thread?
No professional trainer, or knowledgeable person would advocate relying on a loud harmless noise to frighten a criminal who's weapon would be loaded with real bullets.
The only folks who would advocate (or require) responding to lethal force with non lethal force are liberal anti-gun gas bag politicians and activists and the uninformed.
Since you're just asking a question, I won't put you in that category. And, I wouldn't rule out 100% the warning shot as appropriate under certain, but rare, circumstances.
Your assumption that you'd hear him in plenty of time to put on your ear muffs and send him on his way with a loud noise, and that Bubba would act a certain way because that's what you'd do could be hazardous. Sometimes Bubba might answer with some gunfire of his own.