Obviously the pure number of guns have little correlation to the amount of gun violence in a country. The big difference here is that there's serious training involved (probably 15 months), psychology tests, and requirement for locking the weapon up. This is very different from random guy Joe Smith getting a gun and keeping it in his house for "protection". However, gun control needs to go together with better mental health institution, higher income equality etc.
But when it comes down to it, if a crazy person can easily get a hold of a gun, then there will be more shootings. There are two requirements for shooting sprees, 1. Crazy person, 2. Easy access of guns. Try to limit both.