Considering his AWB support was pre-9/11 and he's constantly preaching about the second amendment in relation to fighting terrorism, I think he's figured out why it matters.
So what statements has he made about the '34 act (or gun control in general) prior to his presidential running announcement but after 9/11 is there that shows you with utmost certainty that this new position is genuine? I haven't found anything that's been reassuring, so hopefully you got something.