For millions of Americans, particularly the elderly and physically disabled, the ability to defend themselves against violent criminals can mean the difference between life and death. Yet some of the very firearms that could help them survive have been turned into objects of fear through decades of political propaganda. That is not merely unfortunate. It is dangerous. Let me begin with the deliberate confusion surrounding the term “assault rifle.” Historically, an assault rifle is a military weapon capable of selective fire, both fully automatic and semiautomatic. The ordinary civilian AR-15 is not such a weapon. It fires one round with each pull of the trigger. It is a semiautomatic rifle, regardless of what its political opponents choose to call it. The term “assault weapon” has been promoted and expanded in political campaigns and legislation to include semiautomatic firearms based partly on their appearance and particular features. Gun control advocates have successfully asso...