I read somewhere else that even anti-gun people have a smile on their face after then finish firing a magazine at the range. A reasoned, respectful response, with follow-up questions answered, and an offer to take them to the range, is a great way to go.
I actually like the implication that I'm "otherwise a nice guy". It means they know me, understand something about me, and so will be able to change their attitudes and feel comfortable with their own gun ownership should they decide to switch sides.
We have to understand that we are on the leading edge of this debate, and we know how the MSM, the Brady Bunch and others are manipulating most people, BUT the people being manipulated don't know that. They think their question is perfectly reasonable, and to respond with acrimony or sarcasm only reinforces the negative stereotype the MSM is creating. If every gun owner a person meets is opposite of what they see on TV, they'll soon start learning that they are being manipulated, and when that happens, we have a new member in the club.