Michigan Compiled Laws, Chapter 600. Revised Judicature Act of 1961 § 600.2951

(a) “Approved signaling device” means a pistol that is a signaling device approved by the United States coast guard under regulations issued under 46 USC 3306 or under 46 USC 4302, or predecessor statutes, and including, but not limited to, 46 CFR parts 160 and 161.

(b) “Pistol” means a firearm, loaded or unloaded, 26 inches or less in length, or any firearm, loaded or unloaded, that by its construction and appearance conceals it as a firearm.