So what? If 1 guy kills 30 people or 1 guys kills 3, its still murder and a mass shooting. It was even more devastating in Norway because that many people died.
Should Norway have even stricter gun controls? How strict can you be to 100% absolutely stop gun violence? The answer is you cant.
I firmly believe that if citizens are armed, it does more to prevent gun violence (AND CRIME) than promote it.
Think of it like this. If I am an intruder, and I know that no one on a particular street has any guns, am I more or less likely to rob / hurt / kill people, then if I know that 70% of the people on that street have a gun?
I sure as hell would think twice about breaking into someones home if I felt there was a chance they could have a gun and shoot and kill me for entering their home.