The one primary reason that we need semi-automatic weapons is clarified by the writer of the second amendment himself. In truth, if you read several other comments made by him, you will see that we need fully automatic weapons, rocket launchers, cannons, and any other threatening piece of equipment. It is not about hunting or even self defense. It is about defending our constitutional freedom from foreign AND domestic threat. We need to be able to instill fear in self serving politicians. A well armed individual is a citizen. An unarmed individual is a subject.