The fact that gun related murders are down doesn't mean that they are low. They are still much higher than any other first world country.
Also, even though gun murders are down, gun assaults are up. Part of this discrepancy is due to improvements in emergency medicine -- you are more likely to survive a gunshot wound than a decade ago.
Finally, the gun crisis is not an overall violent crime crisis. Rates of violent crime have been dropping, and are not higher than the rest of the world. The problem is, there are a lot more guns and gun crimes in the US, and gun crimes are much more deadly than non-gun crimes.