This may come as a shock to some of you, but there are many people wearing our nation's uniforms who are anti's. I know this, because I am on active duty (Navy) and work alongside quite a few of them. I did do my part on a couple of them, though, and one of them is now an avid shooter who works part-time as an armed security guard.
But too many of the guys in my shop think that the average Joe out there ought not have a weapon at his disposal. I have found that the best way to change someone's mind is to ask questions that force them to think rather than simply forcefully stating your opinion. If you do that, regardless of how right you are, they simply have to offer back their own opinions with similar resolve, and you will have reached an impasse. I usually don't bring the subject up, as I am the shop "gun nut", but anytime a story makes the news we end up having a discussion about it. I usually try to go the following route:
1.) Do I have the right to be secure in my own home and to protect my family in that environment? (usually replied to in the affirmative)
2.) Should my right to be secure, and to protect my family, be restricted to the home only, or should that also be the case when we are out and about minding our own business? (also usually replied to in the affirmative)
3.) Should I retain the right to use deadly force against anyone who is attempting to use deadly force against me, a member of my family, or any other person if I am able to come to that person's aid?
4.) Should I retain the right to carry a firearm in a concealed manner in order to make myself available to defend myself, a member of my family, or anyone else who might need my help?
Questions such as these, when posed in a non-threatening manner, will generally cause the other person to at least stop and think for a minute. And once you get them past emotion and into the realm of actual thought and reason, you are on your way to winning the victory on the most important battlefield in this war: the space between their ears.