The real problem with rational basis is this: Under rational basis, a law will be held constitutional if there is any rational basis for which the gov't could have passed said law. It doesn't even matter if the reason found by the court was the reason stated by the legislature. ANY rational reason will do.
However, given that the RKBA has been held to be a fundamental, individual right, something higher than rational basis is in order.
I'm a lawyer, but I'm not your lawyer. If you need some honest-to-goodness legal advice, go buy some.