As for your 4 points...
1) Demonstrate how it is? Are you a knee-jerk "shall not be infringed" guy? I suggest you look up the definition of infringe. Infringe is not the same as regulate.
I've already pointed out the reasons why it's unconstitutional, and I haven't even mentioned the 2A. Tell me sir, what ENUMERATED POWER gives the national government this authority? Not your nebulous "general welfare" clause. That's a non-starter. It is NOT a source of power or legal authority.
2) You'd be laughed out of the room in most serious circles stating there isn't any problem with criminals buying guns from legal sources.
Criminals buying guns from legal
sources? So what. Are they LEGALLY buying? NO! They're not! It's already illegal! How will making it more illegal stop them? It won't.
3) 120k preventions in 2 years... it arises from that documented proof, actually. Your outlying events not withstanding. No system is perfect, if someone suddenly snaps there is really no way to prevent it. However, preventing known wackjobs from getting guns is something we ought to pursue dilligently... since it doesn't stop law abiding people from getting a gun.
Since no "known wack-job" that has committed a mass shooting has acquired their firearms through a method that would have prevented it, had these "universal" checks been in place... what's the point?
4) And needs to be strengthened so as not to be violated so easily... I'm all for pursuing people who falsify on 4473s.
Making it "universal" doesn't strengthen it so it's not violated so easily. Criminals are funny, in that they tend not to obey laws. You know, drug dealers who buy and sell products that can not be legally obtained by ANY method? By. Any. Method. Yet, there they are, by the millions, buying and selling. Oh, yeah, they've got guns too. Illegal guns. All their guns are illegal. They were acquired illegally or possessed illegal, or both. Still... There. They. Are.
These proposed restrictions only stop or hinder law abiding people. People who follow the law. People who, by definition, are not the people we worry about stopping.
That, in itself, should end any serious discussion. What's the point in stopping people who aren't dangerous? If that's not enough, there are the constitutional issues. If that's not enough, nothing will be.
This is the very definition of a circular argument and I've said all I can say. This "is not!", "is too!" is pointless.