Lock core assembly for a cylindrical lock

A lock core assembly comprising, in combination:

• a knob including a first end face with a lock core opening and a second end face with a spindle projected from the second end face, a slot being defined in the spindle and having an extension extended into the second end face, thereby defining two stop wall portions on two opposite sides of the extension of the slot, the two stop wall portions positioned on the second end face of the knob;
• and
• a lock core assembly including a barrel with two ends and a lock core rotatably mounted in the barrel, the lock core including two ends extended beyond the ends of the barrel, respectively, one of the ends of the lock core being located in the lock core opening, the other end of the lock core including an actuating member mounted thereto, the barrel including a protruded top portion with at least one lateral wing bearing against the stop wall portions of the knob.