Technically, we should be talking about correlation rather than causality.
There is no correlation between increased firearms and increased crime. There IS a correlation between increased firearms and decreasing crime. As others have said, there are far too many variables to even guess as causality but, like I said before, that won't stop the antis from making all the causal arguments that you can shake a stick at.
Still happily answering to the call-sign Peetza.
You do not HAVE a soul. You ARE a soul. You HAVE a body.
He is no fool who gives what he can not keep to gain what he can not lose.
-Jim Eliott, paraphrasing Philip Henry.