Early reports said that Zimmerman's gun (Kel-Tec 9mm Semiautomatic pistol) was recovered at the scene with a full magazine and one empty shell casing in the chamber. I've been thinking about the failure of the pistol to extract the empty case and chamber a live round from the magazine. The only answer I can come up with is Martin grabbed the gun with his left hand grasping the slide. The two men then wrestled for possession with the muzzle pointing at Martin's chest. If Zimmerman had his finger in the trigger guard and Martin pulled the pistol towards himself, the gun might have discharged the chambered round but failed to cycle because of Martin's grip on the slide. In sum, Martin shot himself inadvertently while struggling for control of the gun.
It would be interesting to see a check on Martin's forearms for nitrate residue. I have no doubt of what the outcome would have been had Martin seized control of Zimmerman's pistol!
Regards,
GtG
PS Karma is a bitch...