A: No. The Federal Gun Control Act (GCA1968), at 18 U.S.C. § 922(g)(3), prohibits any person who is an “…unlawful user of or addicted to any controlled substance (as defined in section 102 of the Controlled Substances Act (21 U.S.C. 802))" from shipping, transporting, receiving or possessing firearms or ammunition.
Marijuana is listed in the Controlled Substances Act as a Schedule I controlled substance, and there are no exceptions in Federal law for medical marijuana, even if such use is allowed by State law.
(2) May a user of MEDICAL marijuana purchase or possess a firearm or ammunition?
A: No. Medical marijuana users are prohibited under Federal law, even if State law allows the medical use of marijuana. As per the ATF’s “Open Letter to All Firearms Licensees” it states “ if you are aware that the potential transferee is in possession of a card authorizing the possession and use of marijuana under State law, then you have "reasonable cause to believe" that the person is an unlawful user of a controlled substance. As such, you may not transfer firearms or ammunition to the person, even if the person answered "no'' to question 11.e. on ATF Form 4473.”
(3) May a user of RECREATIONAL marijuana purchase or possess a firearm or ammunition?
A: No. Recreational marijuana users are prohibited under Federal law, even if State law allows the recreational use of marijuana.
(4) May a Licensed Dealer (FFL) or a private seller TRANSFER firearms or ammunition to a marijuana user?
A: No. Federal law, 18 U.S.C. § 922(d)(3), makes it unlawful for any person to sell or otherwise dispose of any firearm or ammunition to any person knowing or having reasonable cause to believe that such person is an unlawful user of or addicted to a controlled substance.
As provided by 27 C.F.R. § 478.11, “…an inference of current use may be drawn from evidence of a recent use or possession of a controlled substance or a pattern of use or possession that reasonably covers the present time."
As per the ATF’s “Open Letter to All Firearms Licensees” it states “…any person who uses or is addicted to marijuana, regardless of whether his or her State has passed legislation authorizing marijuana use for medicinal purposes, is an unlawful user of or addicted to a controlled substance, and is prohibited by Federal law from possessing firearms or ammunition. Such persons should answer "yes" to question 11.e. on ATF Form 4473 (August 2008), Firearms Transaction Record, and you may not transfer firearms or ammunition to them.”
"LOOPHOLES & PITFALLS"
Bang or Bong, you cannot have both! It is that simple. Until such time as the Federal Government removes marijuana from Controlled Substances Act as a Schedule I controlled substance, you must choose either guns or weed. If you choose both, you face 10 years in Federal Prison if caught. It does not matter at all that New Jersey has legalized marijuana. The Federal law is an entirely separate jurisdiction.