Until eventually an unstable one (possibly a substitute) decides to start shooting the kids.

Then the solution will obviously be to arm the students.

Are you suggesting Biden and Congress wouldn't do those things if the Democrats had a filibuster-free majority in the Senate?  Your claim that Democrats don't do anything when they are in power fails to recognize that they have not had sufficient legislative power to unilaterally act on gun legislation since 1977. 

Then I would suggest them not to promise stuff they can't do. 

Bad look.

Then I would suggest them not to promise stuff they can't do. 

Bad look.

+++

So you say that a presidential candidate shouldn't say what their plans for the future are? Isn't that far worse than not being able to fulfill promises because of lack of majority in the Congress?

Yes, welcome to the American political system.  Any promise a presidential candidate makes carries with it the implicit qualifier "if Congress will enact the law necessary to make this happen."  Yes, Biden could have been realistic and said something like "I'll try to get Congress to ban assault rifles and high capacity magazines, but the Republicans will filibuster and prevent the law from being passed and nothing will happen."  But that probably wouldn't be a winning campaign strategy.  Maybe there wasn't much of a chance he'd be able to get gun legislation enacted, but if he'd lost the election there would be zero chance.

More to the point... you've suggested that voting for Democrats is useless in terms of addressing the gun problem.  But voting for Democrats is actually the most potentially effective thing people can do at this point (which is not to say it's guaranteed to be effective, just that any other actions would be even less effective).  The only way to get anti-gun legislation enacted is to either elect enough Democrats to be able to do it, or to persuade some Republican members of Congress to support the idea.  And the only thing that will persuade those Republicans to change their position would be if that position became a liability in terms of getting re-elected.  They aren't going to be convinced by protests, or lectures, or public shaming, or a bipartisan commission.  They support unlimited gun rights because it helps them win elections, and changing that fact would be the only way to change their position.