I agree that Zimmerman should not have been armed with a gun. He should not have gotten out of his car. He should not have engaged with Martin. He should not have shot his gun. Hell, he should not have been involved with a neighborhood watch program, it seems he was too eager. However, I do have one question. Since Zimmerman shot only one time, what difference does it make whether he used a semi-auto handgun or any other kind of handgun?

...you're also missing the point that the semi-automatic handgun has become ubiquitous in our society. It's almost a fashion statement.