MD has a pre-emption law.
This doofus ought to check the law before running his mouth:
Criminal Law - §4–209.
Public Safety - § 5-133.
Public Safety - § 5-134.
Local governments are prohibited from regulating the purchase, sale, taxation, transfer, manufacture, repair, ownership, possession and transportation of handguns, rifles, shotguns and ammunition, with some exceptions.
Localities may regulate the purchase, sale, transfer, ownership, possession and transportation of such firearms and ammunition with respect to minors; law enforcement officials of the local government; and activities in or within 100 yards of "a park, church, school, public building, and other place of public assembly."
(note that taxation is not included in the approved "exceptions")