The suicide rate in the US is twice that of the UK - take from that what you will, but brits are as a whole a pretty depressed bunch, and I dare say gun availability is a factor in suicide prevalence - the professions with the highest rates of suicide tend to be those that easily provide the tools to definitely painlessly kill yourself - doctors, dentists, veterinarians, farmers.

I'm hypothesising, but I honestly think reducing availability of firearms would cause more people to not be able to kill themselves with facility, and therefore more likely to have the time to reconsider or seek help.