I recall reading of a study that found that gun bans initially reduce suicides. On a linear chart, the suicides fall off, forming a trough, but then curve back up, but don't stop at the initial level, they curve up and form a hill, then fall back to the initial level.
It was theorized that those people were stymied in trying to kill themselves, but eventually grew so determined they simply found another way. Removing the firearm didn't treat the motivating cause.
I cannot recall, however , where I found this study.