An ER doctor, Emmy Betz, talks plainly about suicide and gun availability in this TED talk ...
In other words, means matter, and guns are the most lethal means available for suicides.
Some good quotes:
"But I also ask [the patient] a question - an important question - that I think we all need to be asking anyone at risk of suicide. Do you have access to a gun?"
"But the thing is, this is not political. This is about helping protect the people we love, the people we care about, when they are in times of crisis."