While I obviously agree that interventions targeted at behaviour are good, there is evidence that suggests that the guns really are a problem in relation to suicide:
From a Study published in the New England Journal of Medecince in 2008 (authors = Miller and Hemenway)
The empirical evidence linking suicide risk in the United States to the presence of firearms in the home is compelling. There are at least a dozen U.S. case–control studies in the peer-reviewed literature, all of which have found that a gun in the home is associated with an increased risk of suicide. The increase in risk is large, typically 2 to 10 times that in homes without guns, depending on the sample population (e.g., adolescents vs. older adults) and on the way in which the firearms were stored. The association between guns in the home and the risk of suicide is due entirely to a large increase in the risk of suicide by firearm that is not counterbalanced by a reduced risk of nonfirearm suicide. Moreover, the increased risk of suicide is not explained by increased psychopathologic characteristics, suicidal ideation, or suicide attempts among members of gun-owning households.
The relevant finding: Having a gun in the house is a risk factor for suicide that is not, repeat not, counterbalanced by people using a different means to kill themselves if a gun is not around.