I just read your blog. Just a technical point I'd like to make, guns don't "go off," they're fired. To be certain, Zimmerman fired his gun at Martin with lethal intent.
There is a question in all this I don't really know the answer to. If Zimmerman was the aggressor and your story is fairly accurate, at what point does Zimmerman surrender his right to self-defense? If I can make a loose analogy, just because a girl is making out with you and wearing provocative clothes (or not wearing clothes) she retains the right to say "no" at any point. So, even if Zimmerman was following Martin and harassing him, does that mean he has surrendered his right to defend himself should Martin react to the harassment by attacking Zimmerman? Unless Zimmerman struck first Martin would have committed a crime by physically attacking Zimmerman, correct? So doesn't Zimmerman have the right to protect himself from an illegal physical attack?
Now, to me this is actually a big problem for supporters of individuals' right to self defense and by extension the right to use firearms for self defense. If I can basically taunt someone, sort of like the big brother poking at his little brother while saying "I'm not touching you, I'm not touching you," then when the person being taunted responds I pull out my firearm and kill them and claim justified self defense. That's not okay in my book, even though I'm a very avid supporter of a person's right to defend them self. I think that's what may have happened in this case. I think a clearer guideline needs to be established based on this case.
I accept your point about guns, but since I have no experience with them, I would not offer such a conclusion on my own.
I don't know where the legal line is or should be. As far as I'm concerned, morally and ethically, Zimmerman waived his claim to self-denfense when he became the aggressor, pursuing someone who was running away. If he had seen Martin committing a crime, though, I would probably have a different opinion on that.