Editing Vickers machine gun (section)

==Use==
[[File:PrincessPatriciasCanadianLightInfantryTrainingMaximGunDec1942.jpg|thumb|Soldiers of Princess Patricia's Canadian Light Infantry firing a Vickers machine gun during a training exercise, Eastbourne, England, 3 December 1942]]
The gun and its tripod were carried separately and both were heavy. The Vickers Mk I was 30&nbsp;lb (13.6&nbsp;kg) without the water and tripod, and weighed 40&nbsp;lb (18.1&nbsp;kg) with the water. The original design did not anticipate it being carried up jungle-covered mountains on men's backs, but such was the weapon's popularity that men were generally content to pack it to all manner of difficult locations. The tripod would be set up to make a firm base, often dug into the ground a little and perhaps with the feet weighted down with sandbags.

The water jacket would be filled with about {{convert|4|L|gal}} of water from a small hole at the rear end, sealed by a cap. The evaporative cooling system, though heavy, was very effective and enabled the gun to keep firing far longer than its air-cooled rival weapons. If water was unavailable, soldiers were known to resort to using their urine.<ref>{{cite web |url=http://www.royalarmouries.org/what-we-do/research/nfc/single-object/172 |title=Vickers Mk.I machine gun |publisher=[[Royal Armouries]] |access-date=26 September 2012}}</ref> It was sometimes claimed that crews would fire off a few rounds simply to heat their gun's cooling water to make [[tea]], despite the resulting brew tasting of machine-oil.<ref>{{cite book | title=Tea, rum & fags: sustaining Tommy, 1914-18 | publisher=History Press | last=Weeks |first=Alan | year=2009 | page=19 | isbn=978-0752450001}}</ref> In extremely cold weather, the cooling water could freeze and damage the gun. This problem was addressed using an insulating water jacket cover, introduced in 1918 but still in use during the Korean War. Some crews added vehicle antifreeze, others drained the water jacket, or simply fired a few rounds periodically to keep the water from freezing.{{sfn|Pegler|2013|pp=70}}

The loader sat to the gunner's right, and fed in belts of cloth, into which the rounds had been placed. The weapon would draw in the belt from right to left, pull the next round out of the belt and into the chamber, fire it, then send the fired brass cartridge down and out of the receiver while the cloth belt would continue out the left side. During sustained fire, the barrel would heat up which heated the water in the jacket until hot enough for the water to evaporate or boil thereby cooling the barrel releasing the heat through steam. It took the Mk I 600 rounds of continuous fire to boil the water in the jacket, evaporating at a rate of {{convert|1.5|imppt|ml|-1}} per 1,000 rounds.<ref name="vmg.org.uk"/> The steam would reach the top of the jacket and enter a steam tube which led to a port that was situated under the jacket near the muzzle. A hose was connected to this, which released the steam into a metal water can allowing it to be vented away from the rest of the gun hiding the steam cloud and the gun's position. This also allowed any condensate to be reclaimed from the steam. Before the can got too full, it would be emptied back into the jacket to replenish the water level which would have fallen as the water evaporated and boiled away. If the water jacket needed to be emptied, a plug under the jacket could be unscrewed to drain the entire jacket.

[[File:Vickers Clino R.JPG|thumb|[[Clinometer]] for Vickers .303 machine gun]]
The Vickers was used for [[indirect fire]] against enemy positions at ranges up to {{convert|4500|yd|m|0}} with Mark VIIIz ammunition.<ref>{{Cite web|url=https://vickersmg.blog/manual/range-tables/|title=Range Tables - The Vickers Machine Gun|date=4 July 2017|website=vickersmg.blog}}</ref> This [[plunging fire]] was used to great effect against road junctions, [[trench warfare|trench systems]], forming up points, and other locations that might be observed by a forward observer, or zeroed in at one time for future attacks, or guessed at by men using maps and experience. Sometimes a location might be zeroed in during the day, and then attacked at night, much to the surprise and confusion of the enemy. New Zealand units were especially fond of this use. A white disc would be set up on a pole near the MMG, and the gunner would aim at a mark on it, knowing that this corresponded to aiming at the distant target. There was a special back-sight with a tall extension on it for this purpose. The only similar weapon of the time to use indirect fire was the German [[MG 08]], which had a separate attachment sight with range calculator.

A British World War II Vickers medium machine gun platoon typically had one officer in command of four guns, in two sections of two, each with a crew and a small team of riflemen whose job was to protect the gun and keep it supplied with ammunition.