Dunno whether I'm the first person to come up with it, but IMO this is the perfect rebuff to the certainly not untrue, but key-issue-avoiding statement that
Guns don't kill people. People kill people, in the way it's used by "
right to bear arms" people.
Symmetry is beautiful.
If someone replies "But people protect people with guns", you can grin and retort "Well, people kill people with guns".