Your response to that question is certainly clear and concise, and absolutely on-point.
But the kind of response I favor is this, and I would be both ecstatic and relish the opportunity to tell it right to Brandon's stupidly ignorant face:
IT IS NONE OF YOUR **** BUSINESS WHY I WANT, HAVE, OR NEED ANY FIREARM!
The 2nd Amendment DOES NOT grant me the "right" to own a firearm!
The 2nd Amendment PREVENTS GOVERNMENT FROM MAKING ANY LAW THAT LIMITS MY CONSTITUTIONAL RIGHT TO OWN A FIREARM!
And people throughout the country need to understand that distinction, which is of paramount importance in the Constitution!