People are against guns for only 3 reasons. Most are antis out of ignorance and propaganda pressure. They are scared of them because they don't know any better and they get their "facts" from HCI. These are the ones we need to reach out to, because they don't know anything about firearms.
Then you have the true socialists, who believe a better world lies ahead if only the government had the power to make it that way.
The final category is the only one I respect (actually, feel sorry for), those who have been victims of or had a loved one murdered with a gun. Unfortunately their fear/insecurity/grief drives a misguided passion that is used by socialists, and supported by the ignorant.
Unless you had the incredible misfortune to end up with a socialist (don't, you'll hate yourself in the morning) or the extremely unlikely event that this person was a victim, then a rational, semi-literate person should be open to a discussion.
I always try to ascertain which category the person falls into. If they are a victim, there is no point in saying anything. If they are a socialist, I save the guns for the finale, and attack their politics and economics first. It is just blood sport for me. If they are the ignorant, then by God, it is your duty to educate them.
I am a foreigner, and one of the first things I discovered when I got here was that most American men have been cowed into being lame-assed by PC, feminism and especially sexual harassment. I was surprised by how many women I met that were excited by the fact that I was not. I am not a macho, gung-ho idiot. But I speak my mind and if I think a girl wants a hand on her thigh then that's where it is going. Most women want their men to act that way, not to be jerks, but at least to have some male instincts. They like it that guys actually do manly things. Most of the anti-hunting, anti-guns, anti-military attitudes come out of a feminism that preaches total equality, where women can do all the things men do. But most women want no part of killing animals or understanding the empowerment of firearms to protect the family from harm. These are instinctively and through evolution male jobs, and modern women are confused by these paradoxes. People reject what they do not understand. But at a deeper level they instinctively feel more secure knowing that their man can look after them. (Don't tell the feminists!)
I'm going to guess you decided to tell her. I'm also going to guess she was open. I am going to guess it excited her. Chances are you'll see her again?