Your „parts“ bolt, cocking piece, striker and striker nut are not M1903 or later Mannlicher-Schoenauer parts. They are super rare Mannlicher-Schoenauer M1900 parts instead. Though most parts are interchangeable in some way, the safeties are different. A 1900 safety in a 1903 bolt body will not work as it is of shorter length and lacks a notch or cutout at half length. Lacking that cutout, the safety cannot turn.
Here are some photos of the Mannlicher-Schoenauer safeties and bolt bodies, M1900 left, M1903 to the end right. As you see, the parts are not compatible.