Don't be surprised if gun control/confiscation turns into a brother-against-brother battle for you too someday.
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?
Since this nonsense started last month, I have personally lost some friends who believe the 2A should be repealed. It is sad, but....