It's not a breach of Batman's standards for him to use a gun, as long as it's not his own. Let me clarify: Batman never kills, which should ALWAYS be the case. Also, Batman should never carry a gun, because it's his special gadgets that make him interesting.

But Batman is also known to be resourceful. If he disarms a guard and needs to break a window or pop a tyre, why shouldn't he shoot at it?