Only Thing That Stops a Bad Guy with a Gun is a Good Guy with a Gun

Propaganda Tactics Used

Use Simple Phrases to Obfuscate Poor Arguments
The right gets its base to use gun related catchphrases so that they won't think about opposing logic. Such as that only a very small percentage of gun deaths are prevented by non law enforcement "Good Guys with a Gun," and they often actually do more harm than good and make law enforcement's job harder.
Repetition Repetition Repetition
So many conservatives respond with this line after mass shootings or crime that it has become cliche. The "Good Guy with a Gun" phrase uses alliteration to help become a very memorable line to use, and every time it is repeated it spreads the myth that the average "good guy" can successfully stop a "bad guy" if only he or she had a gun.