You could be on to something here.
i.e. To put it another way, Is there a SINGLE social issue that stands as a dividing marker between us "social conservatives" and the "moderates"? {I'm also betting it's pro-life with pro-2nd Amendment close behind}
I don't think the Second Amendment rates as an issue one way or the other for the self-proclaimed "moderates". Most of them don't own a gun and have never fired one. I think they're just indifferent to it.
Abortion-on-demand is the big kahuna for them.