[Exton1]

Oxymoron, a gun designed to kill people, duh. What good would one be that did something else?

[Plutarch]

Oxymoron, a gun designed to kill people, duh.

Uh, I think you are thinking of a redundancy, not an oxymoron.

[amxfan2002]

Actually, guns are not designed to kill people. Guns are designed launch a projectile at a very high rate of speed. The killing of people is where the human factor enters the picture.