I'm actually planning the next of my own Medium posts to be basically about this. To be fair, this goes both ways. As someone who's super left on basically everything except gun control, I would like just once to have someone talk about stricter regulations who actually understands the thing they're trying to regulate.
I think you'd get a lot of public support for this kind of "usage" or "intent"-based restrictions on legal weapon types. It would resonate with a lot of gun owners as well. However, what makes an approach like this pretty thorny to implement is that at some point an agent of the state will need to physically show up at people's doors and demand they turn over the weapons that are no longer legal to possess or be arrested. Obviously there going to be some violent confrontations during these encounters but even worse, this action would completely validate not just the "THEY'RE GOING TO TAKE ALL OUR GUNS!!" viewpoint, but every other reactionary, slippery-slope fear that the folks with this worldview hold. I think it would get really ugly. I happen to agree very strongly that re-evaluating what weapon types are legal to possess is a helpful discussion to have. The practical limitations around removing existing gun types from the population though may limit implementation to something like banning NEW sales of these restricted types and grandfathering in any weapons already in the wild. This clearly reduces the benefits gained by the change significantly and possibly creates more problems than it solves. The Gun Deaths In America data presented in this FiveThirtyEight article is important to consider (here's that subtly in discourse again) when discussing the impact of any propsed legislative change. https://fivethirtyeight.com/features/mass-shootings-are-a-bad-way-to-understand-gun-violence/ Is our goal to prevent deaths from guns? What kinds of deaths? Would the proposed legislation have any impact on suicides, domestic violence, or mass shootings only? Are we proposing something as difficult to implement as confiscating guns door-to-door to only impact 1% of gun related deaths? I liked Seth Meyers recent point about our options: "Congress, are there no steps we can take as a nation to prevent gun violence, or is this just how it is and how it's going to continue to be?" We forget that in a democracy we can always try to change what we value and how we want our country to operate. It may be incredibly difficult to make certain kinds of changes but there is path forward for almost any change we want to make. We have to decide first what we want to accomplish. Perhaps our nation's answer is actually "This just how it is and how it's going to continue to be." I just don't believe our public discourse is capable of a reasoned, practical, and nuanced evaluation of our options. Not even at the theoretical or conceptual level let alone at the implementation level. It's going to be done in the intellectual vacuum of "all guns should be banned, period" vs. "don't touch any of our guns or ammo, period".
Any of the weapons you mentioned as permissible are capable of that kind of damage. And you don't even need a gun -- just ask Timothy McVeigh how important gun laws are. Don't forget too that the worst attack on a school ever committed wasn't Sandy Hook, it was in Bath Township, Michigan, and was done with explosives. Don't get me wrong, I'm not against any and all potential gun legislation. My complaint is that the people generally advocating for them don't actually understand how guns work (cf. the talk about "armor piercing bullets" after Sandy Hook). The result is restrictions that are incredibly arbitrary and don't actually change anything in practice (see: the "assault" weapons ban of the '90s).
The bomb thing is such a ridiculous distraction. Yes, people will always kill people and they will sometimes kill a lot of people in spectacular ways. No, there is no way to kill and maim 600 people in minutes with a handgun, shotgun or hunting rifle with no automatic action. A gun is only made to kill things and it's too easy in this country to obtain such a weapon that is made to kill only people such as an AR-15. Why does it matter if assault weapon is a vague term? Can't we just have common sense about what a person should be able to and for what purposes they can own it? "Well, determined criminals will be able to get anything on the black market no matter what you legislate." Yeah, I guess if they can afford the resulting black market prices. "Well, I need a gun to protect myself from a tyrannical government. That was the intent of the right to bear arms." No, you'd need a fucking Abrams tank and a shoulder mount anti aircraft missile launcher and you'd still get the shit killed out of yourself and your little militia. The time of rising up violently against the government is long passed. Every argument for not regulating guns based on acceptable usage of them falls apart. That is a good starting point. You can hunt and you can protect yourself. You can't go to the range and fire a machine gun because it's fun because your fun comes with the risk that some maniac will go on a kill crazy murder spree. You know what? Fuck it. You can have a musket and only a musket because that is what the founders intended when they wrote that stupid amendment. And you have to make your own black powder and ammo because why the fuck not.
Your post is exactly the problem. Rather than listening to what I actually said, you're filling in the gaps with the standard NRA rhetoric, and then going against that. This is exactly why nothing will get done.