3.7 Big gun tested at firing range.
General view raising muzzle of 3.7. Gun / modern type of range-finder / men working rangefinder / men lowering muzzle of 3.7. Gun and soldier looks down barrel / soldiers at work on separate instrument the 'Predictor' (which when the range is found will tell exactly where the plane will be when the shell bursts).
3.7 Gun firing twice. / 3.7 Gun firing.
3.7 Gun firing, empty shell case falls out of breach / 3.7. Gun firing / Gun firing and shell falling out of breach / 3.7 Gun firing.
Background: 3.7 Big gun tested at firing range.