As a peace officer working in the US, I view all these "amesty" drives as a complete waste of time. The least violent crime I've ever observed was while I worked as a deputy sheriff in the west, where every pickup truck had a rack of guns in the back window, and any citizen had the right to carry a handgun on their hip (unless it was concealed).
By contrast, the most violent crime I've ever seen was in a jurisdiction with long standing stringent weapons laws.
As to knives; even in prison, inmates manage to make shivs out of such diverse materials as tooth brushes and spoons, and stab each other with them.
It is my firm belief that law abiding citizens should be allowed to own and carry weapons. Felons should not.
Three years ago, the Minnesota State Legislature introduced a statute allowing any non-felon to carry handguns, concealed, or not concealed. Incidence of violent crime has gone down.
The only complaint about this statute, among gun owners, has been the cost. It now costs $100 for a permit to carry, where before it cost $10 and required convincing the chief law enforcement officer in each county or city of a special need for protection.