if its .gov owned then mcl 123.1102 applies.
123.1102 Regulation of pistols or other firearms.
A local unit of government shall not impose special taxation on, enact or enforce any ordinance or regulation pertaining to, or regulate in any other manner the ownership, registration, purchase, sale, transfer, transportation, or possession of pistols or other firearms, ammunition for pistols or other firearms, or components of pistols or other firearms, except as otherwise provided by federal law or a law of this state.
History: 1990, Act 319, Eff. Mar. 28, 1991
nothing they can legally do to restrict your otherwise lawful carry. Note they can still restrict discharging and attempting to take game.