TRANSFERABLE MACHINE GUNS

HOW DOSE A TRANSFERABLE MACHINE GUNS WORKS

A machine gun is a fully automatic, rifled autoloading firearm designed for sustained direct fire with rifle cartridges. Other automatic firearms such as automatic  and automatic rifles (including assault rifles and battle rifles) are typically designed more for firing short bursts rather than continuous firepower, and are not considered true machine guns.

As a class of military kinetic projectile weapon, machine guns are designed to be mainly used as infantry support weapons and generally used when attached to a bipod or tripod, a fixed mount or a heavy weapons platform for stability against recoils. Many machine guns also use belt feeding and open bolt operation, features not normally found on other infantry firearms.

Machine guns can be further categorized as light machine guns, medium machine guns, heavy machine guns, general purpose machine guns and squad automatic weapons.

Similar automatic firearms of 20 mm (0.79 in) caliber or more are classified as auto cannons, rather than machine guns.

Operation

Many machine guns are of the locked breech type, and follow this cycle:

• Pulling (manually or electrically) the bolt assembly/bolt carrier rearward by way of the cocking lever to the point bolt carrier engages a sear and stays at rear position until trigger is activated making bolt carrier move forward
• Loading fresh round into chamber and locking bolt
• Firing round by way of a firing pin or striker (except for aircraft medium calibre using electric ignition primers) hitting the primer that ignites the powder when bolt reaches locked position.
• Unlocking and removing the spent case from the chamber and ejecting it out of the weapon as bolt is moving rearward
• Loading the next round into the firing chamber. Usually, the recoil spring (also known as main spring) tension pushes bolt back into battery and a cam strips the new round from a feeding device, belt or box.
• Cycle is repeated as long as the trigger is activated by operator. Releasing the trigger resets the trigger mechanism by engaging a sear so the weapon stops firing with bolt carrier fully at the rear.

The operation is basically the same for all locked breech automatic firearms, regardless of the means of activating these mechanisms. There are also multi-chambered formats, such as revolver cannon, and some types, such as the Schwarzlose machine gun etc., that do not lock the breech but instead use some type of delayed blowback.

Design

Most modern machine guns are of the locking type, and of these, most utilize the principle of gas-operated reloading, which taps off some of the propellant gas from the fired cartridge, using its mechanical pressure to unlock the bolt and cycle the action. The first of these was invented by the French brothers Claire, who patented a gas operated rifle, which included a gas cylinder, in 1892. The Russian PK machine gun is a more modern example.

Another efficient and widely used format is the recoil actuated type, which uses the gun’s recoil energy for the same purpose. Machine guns such as the M2 Browning and MG42, are of this second kind. A cam, lever or actuator absorbs part of the energy of the recoil to operate the gun mechanism.

An externally actuated weapon uses an external power source, such as an electric motor or hand crank, to move its mechanism through the firing sequence. Modern weapons of this type are often referred to as Gatling guns, after the original inventor (not only of the well-known hand-cranked 19th century proto-machine gun, but also of the first electrically powered version).
They have several barrels each with an associated chamber and action on a rotating carousel and a system of cams that load, cock, and fire each mechanism progressively as it rotates through the sequence; essentially each barrel is a separate bolt-action rifle using a common feed source. The continuous nature of the rotary action, and its relative immunity to overheating allow for a very high cyclic rate of fire, often several thousand rounds per minute.