No, any illegal use or addiction to a wide array of drugs makes it a crime for you to own, possess, buy, sell, transport, etc., a firearm, and separately a crime for anyone to knowingly sell or transfer one to you. Marijuana is included, and because it is a Federal Schedule I narcotic, all use is, by definition, illegal use, even state-permitted medical use (and even though there is a federal policy against direct enforcement of the federal prohibition of marijuana against state legal use, this policy does not extend to the criminal firearms exclusion tied to it.)

The quasi-legality of state-permitted and federally-prohibited-without-direct-enforcement is kind of an awful trap, and that’s even before you consider the risks if the federal enforcement pause – which doesn’t change the criminal law and thus would not raise ex post facto concerns for enforcement against acts that occurred during (or before, if the statute of limitations allows) the pause – were to be lifted.