"NO CALIBRATION REQUIREMENTS, SIMPLE INSTALLATION AND OPERATION, NO BATTERIES REQUIRED; GUN RECOIL SIMULATOR IS A SIMPLE BUT EFFECTIVE DEVICE DESIGNED TO FACILITATE TESTING OF THE EXTERNALLY POWERED BOEING ARMAMENTS 25 MM CHAIN GUN AND ITS CONTROL CIRCUITRY. CONNECTED INLINE BETWEEN THE CHAIN GUN AND THE GUN CONTROL UNIT (GCU), THE RECOIL SIMULATOR PROMPTS THE GCU TO INITIATE NORMAL CYCLING OF THE GUN IN SINGLE SHOT (SS) 100 AND 200 ROUNDS PER MINUTE (RPM) RATE; THE GUN RECOIL SIMULATOR HAS A TWO-POSITION ON/OFF SWITCH"