Are you going to continue asking the same questions over and over and ignoring the fact that we have already answered this?
Again... he chose to use guns. Why he did, I do not know for certain. Given what he stated, my guess is he was trying to emulate the joker (as he said he was). That said, it doesn't matter why he chose the guns. The point is that he could have just as easily chosen bombs. Which again means that blaming guns for this is not logical given that he could have simply chosen bombs if he did not have access to guns.
I am just copying your style of posting,asking the same question over and over when the answer doesn't fit my thinking, am I bothering you?