Paragraph about machine gun in ww1

By 1939, the bulk of infantry training centred around the machine gun. In the inter-war years, machine guns had become more reliable even though the basics remained the same. Two types of machine guns had developed - heavy and light machine guns. Light machine guns were designed to be mobile and to move when its carrier moved. Heavy machine guns, while mobile, were more likely to be used when dug in for defensive purposes. They also had a greater rate of fire than a light machine gun that tended to rely on being magazine fed (like the British Bren gun) as opposed to being belt fed like a heavy machine gun. Heavy machine guns usually had better gun-sights on them and could sustain heavier and more accurate fire on an enemy position.

The Russians at the start of the war used the 12.7mm heavy machine gun. It was to remain standard issue throughout World War Two. It was gas-operated and used air to cool it. It weighed just under 79lbs (about 5.5 stone) and was moved on a two-wheeled mounting. The 12.7mm gun was over 60 inches in length and had a rate of fire of between 540 and 600 rounds per minutes (rpm).

The machine gun, which so came to dominate and even to personify the battlefields of World War One, was a fairly primitive device when general war began in August 1914. Machine guns of all armies were largely of the heavy variety and decidedly ill-suited to portability for use by rapidly advancing infantry troops. Each weighed somewhere in the 30kg-60kg range - often without their mountings, carriages and supplies.