hi dig,
of course, it takes years (and decades) to remove guns from a society.
but that a country like brazil can lower the rate of violence is encouraging. it shows that changing laws can have an effect.
obviously, there are going to be anomalies in the statistics. these may be random. they may be due to enforcement issues. lots of causes of static.
ideally, you want the rate of gun ownership like the uk, in which deaths by arms are vanishingly small.
or you choose a "free" model, in which you stop pretending that widespread ownership of weapons isn't the cause of the problem. And that killing ducks is more important than saving children.
I think the former is more free, myself. But you choose your freedoms. Freedom to shoot ducks. Freedom for children to remain alive. Tough choices.