Mich. Comp. Laws § 28.5a

Sec. 5a. (1) Beginning on the effective date of the amendatory act that added this section, the department shall dispose of all firearms that are purchased by a municipality under a gun buyback program and turned over to the department. (2) The department shall dispose of all firearms described under subsection (1) by destroying the firearms. The department shall ensure that all parts of the firearms disposed under subsection (1) are destroyed. The department shall not resell any firearm described under subsection (1). (3) As used in this section, "firearm" means any weapon that will, is designed to, or may readily be converted to expel a projectile by action of an explosive.