Google Michigan.gov/DNR. You should be able to find a map delineating the rifle zone from the "shotgun" zone. Rifled slug barrels, muzzleloaders, pistols larger than .35 caliber, and rifles shooting 1.8" straight walled cartridges .35 and larger are legal in the shotgun zone.
The line is basically M-57. North of that line, the .223 is legal for deer and bear.
