Marijuana remains illegal for any purpose in every US state, territory and possession under federal law. Users are prohibited not only from purchasing but also possessing any firearm or ammunition. Legally, you could say yes on the form and be denied, or you could lie and be subject to 10 years imprisonment and a lifetime firearms and ammunition ban. In January 2017 the 4473 question 11e had a warning added about pot still being illegal regardless of what states say. All users are prohibited persons whether you buy a gun or not, for that matter. It's always been that way as far as I know and has never changed.