Fund mental health institutions and make it easier to involuntarily commit people before they buy weapons and go on rampages?

Case after case, you see more red flags than a May Day Parade, but none of it legally actionable or reportable on a background check.

Examples:

https://en.m.wikipedia.org/wiki/Uvalde_school_shooting

"Ramos' social media acquaintances said he openly abused and killed animals such as cats and would livestream the abuse on Yubo.[132] Other social media acquaintances said that he would also livestream himself on Yubo threatening to kidnap and rape girls who used the app, as well as threatening to commit a school shooting.[131] Ramos' account was reported to Yubo, but no action was taken.[131][133]"

https://en.m.wikipedia.org/wiki/Parkland_high_school_shooting

"The Florida Department of Children and Families investigated him in September 2016 for Snapchat posts in which he cut both his arms and said he planned to buy a gun. At this time, a school resource officer suggested[92] he undergo an involuntary psychiatric examination under the provisions of the Baker Act. Two guidance counselors agreed, but a mental institution did not.[93] State investigators reported he had depression, autism, and attention deficit hyperactivity disorder (ADHD). However, psychologist Frederick M. Kravitz later testified that Cruz was never diagnosed with autism.[94] In their assessment, they concluded he was "at low risk of harming himself or others".[95] He had previously received mental health treatment, but had not received treatment in the year leading up to the shooting.[96]"

https://en.m.wikipedia.org/wiki/Sandy_Hook_Elementary_School_shooting

"In a 2013 interview, Peter Lanza (Adam's father) said he suspected his son might have also had undiagnosed schizophrenia in addition to his other conditions. Lanza said that family members might have missed signs of the onset of schizophrenia and psychotic behavior during his son's adolescence because they mistakenly attributed his odd behavior and increasing isolation to Asperger syndrome.[155][162][169][170][171] Because of concerns that published accounts of Lanza's autism could result in a backlash against others with the condition, autism advocates campaigned to clarify that autism is a brain-related developmental disorder rather than a mental illness.[172] The violence Lanza demonstrated in the shooting is generally not seen in the autistic population[173] and none of the psychiatrists he saw detected troubling signs of violence in his disposition.[155]

Lanza appears to have had no contact with mental health providers after 2006. The report from the Office of the Child Advocate stated: "In the course of Lanza's entire life, minimal mental health evaluation and treatment (in relation to his apparent need) was obtained. Of the couple of providers that saw him, only one—the Yale Child Study Center—seemed to appreciate the gravity of (his) presentation, his need for extensive mental health and special education supports, and the critical need for medication to ease his obsessive-compulsive symptoms."[165]"

https://en.m.wikipedia.org/wiki/2022_Buffalo_shooting

"In June 2021, Gendron had been investigated for threatening other students at his high school by the police in Broome County.[20][60][66] A teacher had asked him about his plans after the school year, to which Gendron responded, "I want to murder and commit suicide."[67] He was referred to a hospital for mental health evaluation and counseling but was released after being held for a day and a half.[20][66][68]

Gendron told police that he was merely joking; however, Gendron later wrote online that this was actually a well-executed bluff.[65][69] He was not charged in connection with the incident since, according to investigators, he had not made a specific enough threat to warrant further action.[66][69] The New York State Police did not seek an order from a state court to remove guns from Gendron's possession.[69][70] The mental health evaluation was not an involuntary commitment, which would have prohibited him from buying guns under federal law.[69]"