I read that article. What a self absorbed wank it was, all the while denying realities too painful to address about magazine size.
Magazine size counts in mass slaughter. It's not really needed anywhere else. I bet I've slaughtered more animals with rifle and shotgun than most, if not all, here. Must be getting up into the thousands.
Never with a mag capacity greater than 5, which meant animals escaped in the reloading pause when the mag emptied.
However, in discussions with keen US shooters the honest ones have said the high US firearms fatalities rate, compared to other developed countries, is a price they are quite prepared to pay to keep the present level of access to firearms.
Here's an attempt to analyse the possible effects of some control measures in historic cases.