The Actually Abrams can fire in manual mode with the Commander's or Gunner's palms pressed. Just you will not have no turret or gun movement, Turret and Gun movement would all have to be done manually by the Gunner. Manual Mode does not cut of the trigger circuitry. The only Fire inhibits that cut off the trigger circuitry is the driver's hatch being open, the super elevation or tracking error is too great,Gun Select Switch is in Trigger Safe and Main Gun lever not in the armed position. The Manual firing device ( Master Blaster ) in the Gunner's station primary role is if the Tank would lose it turret power. The Manual Firing Device only fires the Main Gun and will bypass the trigger circuitry.