@Baldimo,
It is about race because if you are a black man or boy, people assume you are dangerous or suspicious as did Zimmerman.
Zimmerman could have shoved Martin which wouldn't leave a mark but which would start a fight. Martin then could have hit him hard to enough to bloody his nose and knock him down, they could have fought on the ground and at some point Zimmerman was able reach his gun which was holstered on his back side, then Zimmerman could have shot him. Or Martin cold have hit first hard enough to knock him down then they rolled on the ground. Martin would have been justified because he had just been tailed and stalked by Zimmerman, Martin was fearful of what Zimmerman was going to do to him so he stood his ground and fought him. He wasn't armed, so it was unfair fight from the get go.
Since his gun was located in the back, there was no way Martin could have seen his gun to reach for it in the first place or have succeeded in getting to it even if he did see it.