A Vickers water-jacket holds 7 pints of water, which boils after 600 rounds have been fired at a rate of 200rpm.
It then consumes 1Ѕ pints of water every 500 rounds and after one hour’s firing (10,000–12,000 rounds) at a steady 200rpm the barrel requires replacing.
To do this, the gun is tilted muzzle-downwards, the upper retaining screw on the spade grips is removed and the grips are swung downwards.
The fusee spring is unhooked and the muzzle attachment unscrewed.
When the cocking handle is pulled sharply rearwards it brings the side-plates and barrel backwards out of the receiver as one unit.
At this point, the No. 2 of the gun pushes a cork into the muzzle aperture to prevent water loss and the barrel is replaced.
(If the No. 2 wasn’t wearing gloves before, he will be now, as the barrels and water-jacket are red-hot.)
The reversal of this procedure puts the gun into working condition again and usually some topping-up of the water is required. A good gun team could do this in around two minutes.
