One of the reasons I used to dismiss gun control was that suicides make up an incredibly high percentage of gun deaths in the US. A suicidal person will typically use whatever tool is at their disposal to get the job done*, right? So if we're being real about the scope of our problem, we should remove those from the total. Now, the remainder is still the highest in the civilized world, but much less terrible looking.
* then, I read about suicide. The effective lethality of the means plays a whole lot into it -
https://www.hsph.harvard.edu/means-matter/means-matter/case-fatality/ - where using a gun makes you far more likely to complete the job by any other means. A, unbelievably high percentage of gun-related suicides include a gun purchased just before the suicide. I'm having trouble finding the statistics I read, but
https://giffords.org/issues/gun-suicide/ and
https://www.everytown.org/solutions/waiting-periods/ - these argue that since, in many cases, suicide is a irrational and immediate act, requiring a waiting period would cut down on a not-insignificant percentage of successful suicides. Perhaps the person tries another method, but according to statistics, they very likely won't succeed. Whereas with a gun, they have the aforementioned 85% success rate.
So yeah. Even suicides would be cut down substantially by eliminating the ability to buy guns.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3518361/