The argument that a firearm that kills or injures someone when used correctly is a defective product is a difficult one to make because, well, that's what it was designed to do. However, if a poorly-designed or -built firearm blows up in the user's hand, then that would probably be considered defective, and the injured person might well prevail on a defective-product liability claim.
Maybe companies should design new car models specifically to kill, that way when it happens they can truthfully claim it was exactly what it was designed to do, it would work regardless if it happens by accident or intentional as long as the buyer is not the victim, exactly like with guns.
