PA has no law against firearm ownership for a MMJ patient. Federal law does.
I can't buy a gun if I have a MMJ card. But I can already own one.
Respectfully, that is not correct. Under 18 U.S.C. § 922(g)(3), it is unlawful for any person who is an "unlawful user of or addicted to any controlled substance" to ship, transport, receive, or
possess any firearm. The same prohibition applies to the shipment, transportation, receipt, or possession of ammunition. If one is on medical marijuana, it is a federal felony to continue to possess a firearm even if that firearm was legally purchased before getting the medical MJ card. It is further illegal to buy any ammunition for a gun one already owns. The statute refers to possession and the 2011 "open letter" (
https://www.atf.gov/file/60211/download) refers to possession. The BATFE has been quite explicit that—so long as marijuana remains on the federal controlled-substance schedules—it considers gun possession and medical MJ to be mutually exclusive. Moreover, every appeals court that has addressed the issue has upheld § 922(g)(3). See, e.g.:
https://fedsoc.org/commentary/fedsoc-bl ... -ownership