Take the gun, point it in the air, discharge. Warn the next shot goes through the person you're giving the warning to.
Cops go through this armchair stuff all the time. The point is, that there is a very fine line when the deadly force used was acceptable, and when it isn't. Under the SYG law, he may have had that going for him (Zimmerman), but I know he wouldn't be able to use it here. Convincing a judge that he felt his life was in jeopardy at that point and no other recourse... ify at best. More given the circumstances and how it all came to be.
Er, Cat, you do know that firing a "warning shot" is generally prosecuted in the US? You can fire for real or not, but warning shots are really not allowed. And you better be able to back it up if you do fire for real.
For what it's worth, most independent legal experts have looked at the indictment and said it doesn't warrant a second degree murder charge. In fact, Alan Dershowitz, a liberal legal expert of considerable note from Harvard Law, has gone on record as saying that the prosecutor not only put together an arrest warrant that doesn't hold any water, but one that she herself could be prosecuted for----on a charge of perjury, for withholding evidence---namely the injury reports of Zimmerman and the photos. Legally, those are required in an arrest warrant, (all exculpatory evidence is required to be presented as well as evidence for the prosecution).
As for convincing a judge, as I've said earlier, in the US, the standard is the somewhat vague "reasonable person" test. In other words, if under the same exact circumstances, a reasonable person would conclude that their life would be in danger, or that they would be in danger of great bodily harm if they did not use lethal force, then it is self defense.
Notice that there's no mention of what put you in that situation, though the commission of a crime is generally an exception to the self defense laws. Stupidity, however, is not.
For example, if you walk in a neighborhood that is known by you to be dangerous, and are forced then to use lethal force to defend yourself, that stupidity doesn't not take away your right to use self defense.