Or you could just not let that aspect of your lives affect your friendship, for cripe's sake. Talk about beer, or women, or football, or whatever the two of you can discuss without it being confrontational. Or do all of your friends have to be in lockstep with you on all political/social issues?
I've found that I can pretty much base my opinion of someone off of their opinion on gun control. It's just takes a special kind of person to be anti gun. I can also do this with their opinion on Johnny Cash.