Characters
You can get a lot further with a kind word and a gun than with a kind word.
— Al Capone · The Untouchables

Behind the line May contain spoilers.
Our reading
An editorial interpretation.
The speaker claims courtesy alone has limits, while politeness combined with a weapon gets much better results. The line is darkly witty, treating menace as a persuasive tool that gives gentle words their weight. Its charm rests on the plain admission that fear, not kindness, does the real work.
Context reviewed