Not true. They can still be sued for 'defective' products. Who's to say what the meaning of 'defective' is?
If an internal locking device breaks or malfunctions, is that defective? If a homeowner can't see the little red chamber loaded indicator in a dark room, is that defective? I have a strange feeling that any gun which actually fires and kills an intruder must be defective somehow to the dems.