>>Trump is actually making it worse though -- he signed a bill into law rolling back an Obama-era regulation that made it harder for people with mental illnesses to purchase a gun.

That's the talking point, but as usual it's conflated- since the executive action that was rolled back, automatically watchlisted anybody who receives disability payments and assistance to manage their benefits due to mental impairments. While I understand the purpose of such a rule, this classification does not capture everybody who has mental illness and my understanding of US law is that this rule breached 2nd and 4th amendments since it required no evidence or due process as to whether people need to be kept away from guns or even that they have "mental illness" as it's converted to in the talking point. Sessions' legalist view was that government does not have the power to discriminate in this fashion. This fits with Sessions' view that executive legal activism is bad for democracy and needs to be wound back. I'd also observe that had Trump attempted such a decree, an activist judge in Hawaii could be relied on to strike it down as unconstitutional. ;-)

>>But really I blame congress for their inaction more than I do the president. He *should* be leading and demanding that congress does something - and clearly he has no intention of doing that.

I think you're 100% correct that existing constitutional provisions mean this has to be on Congress. But why have you waited decades before expressing such expectations of POTUS? If it's so easy and obvious, why didn't Clinton, Bush or even Obama push Congress as you now expect? More to the point: what exactly should Congress do, apart from vague slogans about gun control? The latest shooter passed police checks and used a semi automatic weapon that can be legally procured in a similar fashion in New Zealand where firearms feature in only about 1% of violent crime, most of which is suicide. There's something different about US society and if you want it fixed, first you need to figure out what "it" is. The risk now is that "the only wrong decision is not to make one" so you may end up with legislation that marginalizes people who already feel marginalized and own large arsenals they won't give up without a fight.