I brought that up as well, and he said that you track the guns that can accept said magazines. If I understand his reasoning, you can then confiscate said magazines.
I mentioned that it would be a monumental and expensive task to try and get all of them off the streets. He replied that the old ones would be grandfathered, and that the new production of parts magazines etc. would be banned and eventually the old ones would wear out and break.
I asked him why is it that we're punishing the law abiding, and I quote
"The goal isn't to punish the innocent. It's not about what's fair, it's about saving lives. TBH I don't really think there's a need for more gun regulation. These freak school accidents are really insignificant, more people die in car crashes daily than what occurred there. It's just more shocking when it's all in one place. But if there was to be any kind of gun regulation passed, decreasing the amount of semi auto magazine fed weapons on the market would do the most to decrease the lethality against large groups of humans in legal weapons."
I told him is a social problem, not a gun problem and I think this sums up his opinion pretty easily.
"It's a lot easier to take some guns off the market than to change human nature."