Now one might argue that the "primary purpose" for them is their safety and not killing, but no, it's not. That is assuming safety by creating a 'threat of getting killed' to the opponent.

I know this punishment is little harsh (and should be decided on per case basis based on the level of negligence) - but we should also agree that if there's no punishment whatsoever - this will continue happening. Mass killings is a real problem that needs to be solved, and most of them get access to guns in their mom's drawers or something like that.

A significant number of guns used in crimes are stolen, so its too bad that more gun owners don't believe in secure storage like you do. I don't get your "slippery slope" comment, could you expand on this more?

edit: if you were a business that works with poisons and you did not provide adequate security measures, you would be so fined if someone steals the poisons. Then why you as individual wouldn't be responsible for the same thing.