That sounds reasonable. What else? Magazine... Ok, I like calling the thingy that holds the ammo a clip. I grew up that way. I know better than the old rifle, gun thing, but clip just seems right.
The bullet holding thingy wasn’t set, or the gun just jammed.
Either way, wouldn’t the slide lock back? Zimmerman reholstered and waited for police. The police cuffed him and took the weapon from the holster. Zimmerman would have had to release the slide back, right?
Ayoob apparently proposes that Zimmerman pulled his handgun, and a struggle over the weapon ensued, during which Martin grabbed the top of the firearm (the slide that moves back and forth as one fires). Zimmerman pulled the trigger, firing one round into Martin. Because Martin's hand was on the slide, holding it in place, the mechanism by which the weapon would have advanced the next round in place to be fired did not occur.
After firing, Zimmerman's weapon would have appeared to be in it's normal state, however there would be no round in the chamber to be fired.