Just a casual glance at a list of the most notorious serial killers shows that many (most?) of them didn’t use guns to commit their crimes.
Again, guns are simply one of many tools used to commit murder. Even if you could get the guns out of criminal hands (highly unlikely, as these will be the LAST people to turn in any guns), they would still manage to find other tools to violently attack and kill others.
Punishing law-abiding gun owners (many of whom will simply go underground with their weapons, becoming criminals themselves) will not do anything to prevent *criminals* from owning or using guns or any other tool to commit murder or other violent crimes.
