Sure enough:
https://www.mdwfp.com/law-enforcemen...ules-regs.aspx
"Weapons legal for use during the Primitive Weapons season are all archery equipment and primitive firearms."Primitive firearms," for the purpose of hunting deer, are defined as single or double-barreled muzzleloading rifles of at least .38 caliber; OR single shot, breech loading, metallic cartridge rifles (.35 caliber or larger) and replicas, reproductions, or reproductions of those type rifles with an exposed hammer; OR single or double-barreled muzzleloading shotguns, with single ball or slug."