I might try to get my hands on that study, as we had some trainers in the past using previous studies by the same group that didn't correspond to state stats at the time, but I'd like to point out two things about their studies:

1) Their gun in self defense studies http://www.hsph.harvard.edu/hicrc/firearms-research/gun-thre... have stats that do not match the US Dept of Justice

2) I would love to get ahold of the full study for #13 "The public does not understand the importance of method availability." because it would explain their base beliefs on a lot of the rest of the page.

I can't read the study, but lots of cultures in the US attach stigma to suicide(weakness) and to gun accidents(stupidity). Families in these cultures sometimes feel that they share the blame for not properly securing the firearm or not effectively mitigating the suicidal ideations of a depressed family member.

Consider a family with a youth who accidentally shot themselves. Rather than state that it was an accident, the family tells authorities that it was a "suicide".

Consider a family with an adult that chooses to commit suicide. Rather than state that it was a suicide, the family tells the authorities that it was an "accident".