There are two gates in the English Shot Flask dispenser.
The gate nearest the flask is held open by the spring and allows shot to flow to be stopped by the gate at the open end. You can see shot in the picture.
The gate in the front fills the tube and holds the shot in place. The end of the flask is inserted in the muzzle of the shotgun or fowler. The lever is pressed and the leaf gate cuts off the flow of shot in the tube. Releasing the lever closes the front gate and opens the rear cut off gate allowing another measure of shot to enter the tube.
The leaf shape of the cut off gate helps the gate to move through the shot and effectively cut off the flow of shot into the gun.
My measure has three settings although the third setting looks a bit off. I really ought to weigh the shot as there are no markings on the measure.
Does your English Flask have the same measuring configuration as mine? Don't go cutting on the gates just yet. I would hope for some pictures.