A gun isn't very autonomous, though. As tools become increasingly autonomous, it might not always be fair to place blame on the end user rather than the manufacturer.
Are you buying a car that is guaranteed to never be in or cause any form of car-accidents.
Or are you buying a car that will try to it's best to get you from point A to point B.
In an accident with the first example the there is a manufacturing flaw, the car did not meet it's specs.
In an accident with the second example you fucked up, you should not have given the control away and it is your fault. The car did nothing wrong it did what you told it to do.