MLK had a whole arsenal at his house at one point, but he was still about using non-violence to stop the rape and murder allowed by Jim Crowe laws and end the war in Vietnam. People on the left can't reconcile this fact that someone who preaches non-violence would have a ton of guns and try for a CC permit, but they are confusing non-violence with pacifism. MLK and Ghandi were fighting a war using non-violence as their strategy, and it paid off in the long run because it made the opposition look like monsters to normal people. Just because you have one strategy for winning a public relations battle doesn't mean you aren't prepared for someone to kick in the front door. My theory, based on his speech about not making it to the promised land, is MLK knew he was going to die and became more at peace with his martyrdom, so the guns were no longer necessary.
His strategy seemed to pay off. The guy managed to change a whole nation by holding up a mirror and showing everybody how ugly racism was. It's not like all of a sudden 1970 rolled around and the country took a pill and wasn't racist any more, but the hardcore stuff was no longer tolerated and was pushed off into dark corners where it continues to fester.
So speaking of strategy and nonviolence...
Right now gun control leaders are trying to use the same tactics as the Jim Crowe enforcers of the south by bringing forth all the fear and disinformation tactics the media can muster to make gun owners look like irresponsible paranoid preppers who are putting everyone in danger. It's up to us not to take the bait. You are wasting your time going toe to toe with a hard core gun banner. They are a lost cause and will drag you down to their level with emotional arguments. The best you can do is find all the people you know who might be on the fence and bring up the subject to them in a way that doesn't seem forced. Maybe they don't understand everyone here needs a background check and fully automatic weapons are already banned. If they seem interested offer to take them shooting, and you will buy with your time an ally for whom no scary news stories or threatening speeches could ever shake their faith.
What we have going for us are two things. Shooting is fun, and people automatically recognize the value of something that can save their life when they hold it in their hand. It goes from being a dangerous abstract concept to a tangible, practical tool that is worthy of respect.
The only way to make a difference is with people you know. While the events on the national stage are concerning if more gun bans or ridiculous laws are passed most likely it will be on a local level, but fortunately that is where your actions and words will have the most impact.