This definately sounds like a communication issue rather than a gun control/safety issue in that I'm not sure you are going to be able to make any headway with your BF about the hazards of guns in the house. Evidently, that is something he just can't hear. I wonder where his conviction about having guns comes from? Perhaps there is some underlying vulnerability he is trying to deal with.

I think if you are going to resolve this in any meaningful way, there is going to have to be some meeting of the mind and heart, rather than a discussion of the issues and who is right versus who is not.