Abstract: The present invention relates to an automatic bolt hold-open rotating assembly to convert a manual bolt hold-open function to an automatic bolt hold-open function in automatic and semi-automatic pistols and rifles, such as the Ruger 10/22 semi-automatic .22 caliber rifle. The components of the assembly readily replace standard factory components in the trigger assembly and replace the standard magazine. The assembly comprises a magazine with channel cutout, a bolt stop, a bolt stop handle for manual manipulation of the assembly, a bolt stop spring to apply clockwise pressure on assembly, a cartridge detecting lever which also serves as a cartridge ejector pivotably mounted on bolt stop with an extension which interfaces with channel cutout of magazine, a tab protruding from the ejector lever which rides in a slot on the bolt stop to limit pivoting of the cartridge detecting lever, and a lever spring allowing counter-clockwise pivoting of cartridge detecting lever to facilitate insertion of recharged magazine.