It would read: “WARNING: IF YOU OR SOMEONE YOU KNOW IS CONTEMPLATING SUICIDE, PLEASE CALL THE NATIONAL SUICIDE PREVENTION LIFELINE,” said the lawmaker.Sure, that'll help. Somewhere between 66% and 75% of gun deaths are suicides So that should reduce the total of gun deaths significantly. But why stop there? Print this warning on tape and require every hardware store to attach it as a tag to every piece of rope over 1/4" in diameter and longer than 10 feet.
Make the warning tape adhesive, and require it to be attached to every bottle of sleep aids containing more than 10 pills. Ban the sale of large capacity magazines of such medications containing more than 10 pills while we're at it.
Respondents to the survey at the link think neglect of the mental health system is the biggest factor in the number of gun deaths, although this would primarily address only the occasional mass shooting. Those get the headlines even though they don't account for the bigger part of the deaths. More to the point would be thug control but this would affect certain privileged groups more than others so that's likely a non-starter.