You are, of course, correct: None of these measures could possibly work. This is why in the United Kingdom, with its draconian gun control laws, criminals are commonly still armed (because the law doesn't affect them), and crimes against the defenseless population are vastly more common than in the USA. And why the gun buyback scheme in Australia after the Port Arthur massacre was completely ineffective in reducing the frequency of mass shootings, but led to an increase in crime, as people were no longer able to defend themselves without their guns.
Oh, wait; That's all COMPLETE BULLSHIT.
It's almost as though your hypotheses were completely and clearly demonstrated to be false by the observed evidence, but that you continue to trot them out as though they had never been challenged.
ETA: In neither the UK nor Australia is it illegal to own a gun for hunting, or for sports such as skeet and target shooting, or for historical reenactment displays, or for pest and vermin control. If you want to hunt deer in Scotland, or roos in the outback, then the law allows you to own and use rifles for this purpose; Or if you want to stop rabbits from eating your lettuces, you can get a shotgun to use for this purpose (unless you have a criminal record, or are mentally unfit).
You need to be licenced, and you are liable to lose your licence, and be heavily fined, if you do not secure your firearms in accordance with strict rules when they are not in use (including when they are being transported to or from the place where they are to be used); And that you are not permitted to cause 'alarm and despondency' by carrying them in such a manner as to attract the attention of the general public to them. 'Self defence' and 'Home defence' are not considered legitimate reasons to request a licence.
You may not own an automatic weapon, nor a weapon with a magazine with a high capacity, without special permission (for example if you curate a military museum). Weapons that are easily concealed ether require similar special permission, or are restricted in where they may be stored and by whom they may be transported - If you are a member of a pistol club, typically your weapons must be securely stored at the club, and can only be removed from the club by a specially authorized person, such as a licenced gunsmith.
If you want to bring mass shooting frequency down to the levels enjoyed by the UK and Australia, it is perfectly possible to do so without banning guns - as those countries have demonstrated.
Another example you could follow is that of the Swiss - they too have laws that allow for ownership of military style weapons, kept in the home, as part of an historical requirement to defend the nation. But they don't have mass shootings, because the ownership of those weapons (which is in many cases mandatory) is (to coin a phrase) '
Well regulated'. The Swiss attitude and laws fit almost perfectly into the full wording of the US Constitution's Second Amendment. The difference is that the Swiss don't ignore the half that they don't feel like living up to.