My point about the mags is that it doesn't stop the killing. the only thing that stopped the killing when the bad guy stopped shooting. He fired hundreds of rounds. that means he changed magazines multiple times. And as I said before, There are hundreds of millions of magazines out there. Good luck getting rid of those. I have a few magazines from WWII that still function like new.
I agree that gun owners should take more responsibility for their firearms. The problem is where you draw the line. If my car is stolen and someone uses it to run someone down, I'm not liable. If I could I'd rather keep my primary firearms on me at all times. The problem is all the "Gun free zones" that prevent me from keeping control of them. A police officer friend just had her car broken in to and her weapon stolen from it while she was in a "Gun Free" establishment(she didn't want to make a scene and all that, just get in, get her groceries and get out). We cannot maintain control of our firearms all the time if we cannot carry them all the time. Even a safe. I Know of a few people who had their safe stolen from their house. One they even broke the slab.
"I would rather be exposed to the inconveniences attending too much liberty than to those attending too small a degree of it." Thomas Jefferson