Earlier quoted context omitted.
Unless you can show a country's (i.e. Australia's) suicide rate plummeting shortly after banning guns, I'm going to have a hard time believing it has a big an impact as you claim. There are lots of first world countries in EU and Asia where guns are banned that have suicide rates comparible to or higher than the US's (and I have a hard time believing guns are the only thing standing between the US being comparible to…
- After the UK phased out coal gas for central heating, which provided a quick and easy death, overall suicides dropped markedly: [0]. - When Sri Lanka replaced a common pesticide which made it easy for farmers to commit suicide with another one that was not as toxic to humans, suicide rates fell by half: [1] - Many different bridges which were popular suicide sites installed bridges and found that overall suicides d…
- The coal gas phaseout's associated decrease in suicide rates principally affected men; women more readily jumped to other alternatives (as indicated on the graphs). It also principally affected England and Wales (Scotland showed far more modest decreases in suicide among men, and effectively no change among women), which prompted the authors of that paper to exclude Scotland from their conclusions due to the anomalous data; it's possible that Scotland didn't phase out coal gas as quickly, but the drop in suicide-by-CO-suffocation seems to support the idea that Scotland and England/Wales were under the same conditions.
- Per the chart in the Sri Lanka article that breaks down poisoning v. "other specified methods" v. "other means", poisoning actually increased (even ignoring the spike in 1983), and most of the reductions were in the "other means" category (which was completely eliminated by 2005). The "Data for risk factors in suicide" section also details various other factors that are more probable than banning a specific kind of poison (namely: the civil war that was raging in Sri Lanka during almost all of time period when suicide rates fell, consistent with the article's remark that suicide rates do typically fall significantly during times of war).
- The Montreal article only concludes that suicide specifically by jumping did not displace to other jumping sites. It makes no conclusion around other means of suicide (and while suicide rates did fall in general, the article states that this trend began 5 years before the installation of the nets on the studied bridge).
EDIT: in general, I don't feel like any of those sources do an adequate job of isolating these potential causes from other factors; they do demonstrate at least some correlation, but - as the saying famously goes - correlation != causation, and there are numerous other factors that tend to drive suicide rates, especially socioeconomic and cultural.