|Representative Image|Defence Acquisition Council (DAC) has accorded Acceptance of Necessity (AoN) for procurement of 616 General Purpose Machine Gun (GPMG) as per details given below with day and night sights and 87,78,000 rounds of Ammunition. The procurement will be in the Buy Indian category.
A machine gun is a fully-automatic mounted or portable firearm, usually designed to fire rifle cartridges in quick succession from an ammunition belt or large-capacity magazine, typically at a rate of several hundred rounds per minute. Earlier machine guns were manually operated, for example, by turning a hand crank.
Here are two main definitions of the upper limit of calibre for machine guns:
calibre larger than 12.7 millimetre (mm) (.50 calibre)
calibre larger than 20 mm
Larger-calibre automatic weapons are generally referred to as autocannons. In between, there are weapons that have been called by either name depending on other traits; for instance, there have been weapons of roughly 15 mm that were variably referred to as autocannons and machine guns.
All machine guns require the following components:
A feed system to load the chamber. Cartridges can be fed into the chamber by a variety of methods, the most common being magazines or ammunition belts.
A trigger mechanism to fire the round. This includes the actual trigger, a trigger sear to catch the bolt, a bolt and a firing pin, as well as other components. Typically, the act of pulling the trigger causes something to strike the primer on the round in the chamber and disengages the sears. This allows continual cycling of the bolt until the trigger is released. A sear then grabs the bolt or firing pins. This stops the machine gun at some point in its cycle.
An extractor system to eject the spent or misfired cartridge. Usually this is fairly simple. A pin on the side of the bolt catches a ridge on the cartridge and flicks it out an ejection port.