I think the murder rate has actually been going down.... hasn't it?
As far as gun control working in some societies, I would question that. Maybe it's perceived to work when the actual causes for the supposed reduction in crime (the ostensive reason for gun control) was, in fact, something else.
I recall, for example England, which during the period of the twentieth century, enacted ever stronger gun control laws, only to see the murder rate during this time rise 150%. Did the murder rate rise because of the gun control laws or was there another reason and the gun control laws simply result from a misbegotten attrempt to ameliorate a growing murder rate?
IT would be difficult in this case to claim success since the murder rate rose, but steadfast guncontrollers would tell us had the gun control laws not been enacted the murder rate would have gone up, say, 175% or maybe 200%
The problem there of course is those claims are not subject to proof. You can't go back in time, undo the laws, and find out what resulted.
And one can make similar claims about other cultures all of which might involve doing "what if?" scenarios without the law in question being enacted.
I don't think it's ever been scientifically demonstrated that gun control works, ever.
It simply winds up being a tool used by politicians whose end goal, really, is people control, not gun control.