On topic, I agree that no amount of logic or constitutional discussion will sway most antis. They have long ago abandoned that part of their brain and now operate solely with emotion.
You will never convince the anti gun crowd until they or a loved one becomes a victim. Fastest conversion you have ever seen after that though, no extra logic required.
As far as Zimmerman, I am not sure what will happen. From what I have seen there is no way a reasonable jury could convict based on the facts alone - even if you dont think he is innocent, there is certainly a reasonable doubt for his actions. But with the hype, advance threats of riots, etc, who knows?