(Taken from Page 7 of the KEL-TEC SUB-2000 Owner's Manual)
The SUB-2000™ is designed to reduce its overall size down to 16.25 X 7 inches for ease of storage.
This is accomplished by doing the following:
Ensure the weapon is unloaded (no magazine or ammunition in the weapon). Remove any accessories on the top Picatinny rail of the forend. Place weapon in SAFE configuration. Rotate the trigger guard on the weapon down, away from the trigger (1). Upon doing so, the barrel assembly is free to rotate around the rear sight axis (2).
Rotate the barrel assembly until it latches into the latching tab in the buffer assembly.
NOTICE - The latching tab is designed to assist the barrel assembly in remaining closed in storage mode for transportation; the latching tab is NOT designed as a lock or safety for this weapon.
To open the weapon from storage mode, press the latching tab rearward (away from the grip), to release the barrel assembly (1). The barrel assembly is now free to rotate to the chambering position (2).
Upon rotating the barrel assembly down, ensure the barrel assembly positively engages into the trigger guard; there may be an auditory "snap" of the trigger guard re-engaging the barrel assembly.