I must respectfully disagree. If the rod goes "thunk" and doesn't bounce much, there is a ball in the barrel, if the rod is dropped into the bore and bounces the barrel is empty. With just a little experience you will be able to tell the difference just by the sound. This will only tell if the weapon is empty, it will not tell you if the weapon is properly loaded. Just my experience, yours may vary.
"Going to war without France is like going deer hunting without your accordion." —Norman Schwartzkopf