If the Second Amendment states that you have the right to bear arms, surely - the right to fire arms is implicit in that right. Otherwise it would be like putting a clause in the constitution which affirmed people's right to own a car - but not to drive it down the street.
It is implicit within the law and cannot be challenged. If the constitution is to be broken apart at the whim of an administration, then legitimate government will cease to exist. A contract made with any party, including and especially the Nation, is wholly void if any part is void, and such an interference would remove any onus from a citizen to observe any law or regulation depending for its validity on the Constitution of the United States of America.
It is very sad it is even sadder reading some of the hateful and cruel things people are saying on Yahoo Answers alone!