Per current Federal Law, marijuana is illegal, regardless of an individual state's laws about medical and/or recreational use. Additionally, per a 2011 ATF letter to all Federal Firearms License holders (i.e. gun stores), the FFL commits a crime should they transfer any firearm to a holder of a Medical Marijuana Card. 

Furthermore, one would have to lie on ATF Form 4473 (HERE) question 21e which states:

"Are you an unlawful user of, or addicted to, marijuana or any depressant, stimulant, narcotic drug, or any other controlled substance?
Warning: The use or possession of marijuana remains unlawful under Federal law regardless of whether it has been legalized or decriminalized
for medicinal or recreational purposes in the state where you reside."

Therefore, should you wish to own, possess, buy or transfer a firearm or ammunition, you need to surrender your Medical Marijuana Card BEFORE you complete the 4473 form at your local gun store. To surrender your card, you must complete the applicable section on the Flordida Divsion of Health's Office of Medical Marijuana Use's form (available HERE). Follow the instructions, and make sure to include your card when you mail them the form.

ADDITIONALLY, if you have already visited our store in an attempt to buy or transfer a firearm, we require you give us a copy of your signed form and printout of the US Postal Service tracking # showing it has been delivered to the address of the Flordida Divsion of Health's Office of Medical Marijuana Use.  Without this information for us to add to our records, there will be a 100% restocking fee for the firearm (if purcahsed from us), or, if purchased from a different online dealer, the firearm will be returned to them at your expense.