On the basis of G3 (НК91 - commercial designation) the company “Heckler und Koch” developed one of the most extensive families of small arms. To date, it is presented in four calibers - 5,56 and 7,62 millimeter light machine gun, assault rifle and carbine, 9 and 10 millimeter submachine gun. Due to more advanced technology, organization of design and production, G3 and its family significantly surpassed in terms of their prevalence and popularity their Spanish prototypes (G3 and modifications to 90 were in service in 50 countries). Within the family created a large series of machine guns of a single design. In Germany, they did not find application, but they had some success on the foreign market.
Manual machine gun НК21А1
The first, basic, model was the NK21, which was unified with the G3 and the rest of the 7,62-millimeter family models in some detail. The machine gun was created to arm the compartments that were armed with a G3 rifle. His release is discontinued.
The basis of the work of automation is the use of recoil semi-free shutter. At the shutter L-shaped. The return spring is located in the elongated hollow end of the bolt. The combat larva and frame are mounted on the axis of the bore. Long bearing surfaces on both sides of the frame move along the grooves of the receiver. Two rollers, which are mounted on both sides of the combat larva, are held by the front inclined surface of the stem of the bolt, which plays the role of a "locking part". This name is arbitrary, since in this system there is no blocking of the barrel bore, but only slowing down of the shutter release. Rollers are included in the grooves made in the receiver. To eliminate the "jump" when filing the cartridge, the combat larva and the locking part are fixed on the frame with the clamping lever. Placing automatics above the barrel bore axis improves the stability of the weapon when firing in bursts.
Manual machine gun НК21А1
When there is a cartridge in the chamber, the rollers are in a diluted state and are kept in the grooves of the receiver by a locking part. During the shot, the pressure of the powder gases through the sleeve is trying to move the bolt larva back. Before the battle larva can move backwards, the rollers need to get out of the grooves and go back. Rollers, trying to come together, force the locking part and frame to move back. The angle of the inclined surface at the locking part is such that the ratio of the speeds of movement of the combat larva and frame equals 1: 4. Thus, while the rollers are moving to their original position, the frame travels a distance more than 4 times than the combat larva. In this case, the frame takes on most of the recoil energy. The clamping lever, when the frame moves back, frees the battle larva. When the mirror of the shutter moves back a little more than a millimeter 1, the rollers out of the grooves of the receiver go completely. After that, the shutter with the force of residual pressure is thrown back, while the slide frame and the battle larva retain the offset in 5 millimeters relative to each other. The slide frame compresses the return spring and cocks the trigger. The sleeve, which is held by the ejector, hits the reflector with the edge of the cap and is ejected through the window of the receiver in the right direction. The bolt carrier reaches the shock absorber with its end portion, after which it returns forward under the action of a return spring. The war larva from the store takes out the cartridge and sends it to the chamber. The cartridge is hooked by the ejector to the annular recess of the liner, the combat larva stops moving. The offset in 5 millimeters between the slide frame and the locking part is reduced to zero, while the rollers fit into the grooves of the receiver. The combat larva is fixed with a clamping lever. The receiver is made of steel forging. The guides are stamped on both sides. The cocking handle moves along a notch made on the left side of the tubular casing, which is welded above the barrel to the receiver, and can be fixed using a special transverse notch. Screw thread applied to the muzzle of the barrel. There is also installed a sleeve intended for mounting the sleeve for a fire with blank cartridges or a lock spring of a slotted compensator-flame arrester. For a more reliable and smooth extraction of spent cartridges, the chamber has 12 longitudinal Revelli grooves. Unlike the base rifle, the machine gun is equipped with a replaceable barrel with a handle for replacing it. The mass of the barrel is 1700 g. To separate the barrel, you must turn it by the handle, sliding it forward to the right.
Food was carried out from the link tape having an open link. The tape was fed with two turning stars on the left. Receiver equipment was as follows. If the folding tape has a tip, it goes from left to right through the feeder tray and retracts until the first cartridge reaches the retainer. As the shutter passes over the ribbon, its open side of the links should face upwards. If the tape has no tip, the weapon must first be lowered. After the feed mechanism latch is pushed in, the mechanism moves to the left. The first cartridge is placed in the stars of the feeder, they turn to the right. The feeder mechanism must then be returned to its original position. When the reloading handle is lowered, the first cartridge is fed into the chamber from the belt. Moving the shutter when shooting shifts the feeder roller to the right with its lower groove. The roller presses the pusher, which rotates the cam that is worn with the feeder stars on one axis. Asterisks rotate, bringing the next cartridge on the line disilane. The weight of the ammunition box and ribbon on 100 cartridges is 3,6 kg.
The tape receiver, if necessary, can be removed and replaced with an adapter for the magazine, inserted into the receiver and held in it with the help of two latches. The device allows you to use a regular magazine from an 20 assault rifle with ammo cartridges or a two-drum plastic 80 magazine with ammo cartridges that resembles the old MG34 store.
The trigger mechanism is similar to the trigger of a G3 rifle. The shot is carried out with a closed shutter. USM is assembled in a separate case, fastened to the receiver with a cotter pin. It is made together with the trigger guard and pistol grip. The interpreter-fuse box is located above the pistol grip on the left side and has three positions: “fuse” - upper, “single fire” - medium (the trigger moved for a short distance), “continuous fire” - lower (the trigger was displaced completely). The spring-loaded sear has an elongated notch, the protrusion of the trigger enters it. Spring tends to push the sear over the trigger forward. At the same time, the other spring is held by the whisper protrusion. Until the bolt carrier does not take the front extreme position, a shot cannot be made. Only after that the safety sear releases the trigger. After pressing the trigger, the sear turns downwards and triggers the trigger. The descent in the “safety” position is locked, the movement of the whisper up becomes impossible, and the combat ledge will not be able to get out of engagement with the trigger.
The diopter sight had a mechanism for introducing lateral corrections. Assigning the front sight retained the ability of the base rifle to fire from the flame arrester with feathered rifle grenades. The shape of the butt allows you to fire, holding it with your left hand, the butt has a shock absorber. The backplate of the receiver, having a plastic butt when installed on machines, is replaced with a backplate that does not have a butt.
Machine gun adopted in service in the Portuguese army, some countries of Southeast Asia and Africa.
On the basis of NK 21 in 73, they created the machine gun NK 21A1. The main difference was the rejection of the use of the store. Food - only tape. We have upgraded the tape receiver - for refueling the tape, it can be folded down, which speeds up and simplifies this operation. A cartridge box with a ribbon was attached to the bottom of the receiver. These machine guns were adopted in Mexico, Portugal, Greece and other countries. Under the designation HM262 was tested in the United States, however, was not accepted.
The modification of NK 22 (NK 21-7,62x39) was made chambered for 7,62x39. It replaced the barrel, receiver and bolt, but the market for such a machine gun could find it. Modification NK 23 performed under 5,56x45 (American Ml93).
NK21E (caliber 7,62 mm), NK 23E (caliber 5,56 mm) are the latest revision of the machine gun NK 21A1, created on the basis of operating experience. Some of the improvements used in this weapon have led to the durability of the weapon and the increase in its effectiveness. The length of the receiver has been increased by a millimeter 94; elongated aiming line and barrel; reduced the rollback length of the moving parts of automation. Mass increased by 500. USM received a mode of firing with fixed lines each of three shots, respectively, the translator-fuse received another flag position. An improved quick-release barrel grip, front hold grip, winter detachable trigger and trigger guard are installed. New sights with 100 - 1200 m (HK21Е) installations or from 100 to 1000 m (HK23Е) are used, with the ability to be adjusted in the direction and range and to introduce lateral corrections to the wind. Other innovations were special devices that reduce the noise of the shutter, a set of accessories for cleaning, which is now in the pistol grip; barrel for firing blank cartridges and "winter descent" for firing in mittens. Cartridge box with a tape is installed on the lower slots of the receiver in front of the trigger guard.
The feed system of the tapes to the receiver was modified in such a way that now the feed of the tape is made in two stages, the power supply system began to work more smoothly, with less load on the tape and the receiver. During the movement of the bolt forward, the cartridge is removed from the tape. During the movement of the shutter in the opposite direction, at the second stage, the feed to the disilline line is completed. The machine gun NK21E received a barrel on 560 millimeters longer. In the barrel of the NK 23 machine gun, the rifles are made with a stroke of 178 millimeters — for the NATO cartridge 5,56x45; however, there is a modification for the HK 23-1 rifling stroke in which 305 millimeters (for the American cartridge).
Both machine guns were supplied with bipods that have three fixed height settings that can rotate 30 degrees horizontally in each direction. Bipods are fixed in a T-shaped curved slot in the back or front of the barrel housing. A characteristic feature of the bipods were concave supports, which allow them to be put on the railing, the side of the car, and the like. The NK 21 machine gun was created as a single one, so its “descendants” can also be mounted on a 1102 model tripod machine, as well as other installations developed by Heckler & Koch (2700 universal turret, 2400 pivot). The depreciated 1102 machine weighing 10,2 a kilogram is supplied with mechanisms of horizontal and vertical aiming, sliding back legs. The machine gun can be equipped with an optical panoramic sight. However, given the power and effective firing range of the 5,56-millimeter cartridge Ml93 or the NATO 5,56 millimeter cartridge, the HK23Е1 can be considered as a light machine gun with the possibility of installation on the machine, and not as a single one. Among the export options have developed a version under the NATO cartridge 5,56x45, and the Soviet 7,62x39, which made the machine gun many-sided. The machine gun was altered by replacing the receiver's guide tape, bolt and barrel.
Light machine gun NK23
The barrel of the NK 21 machine gun is weighted slightly, so it can withstand intense shooting poorly. In Portugal, NK21 was produced under license, in Greece - NK21A1 (ENK21A1), in Mexico - NK21E, in Italy, Franky, but based on NK23E, produced its own LF / 23E machine gun with a polygonal barrel cutting. This machine gun is another example of the close and long-standing cooperation of German and Italian military-industrial companies. Minor differences are associated with the features of manufacturing technology in Italy. The length of the machine gun was 1030 millimeters. The chrome-plated barrel (the length of the rifling stroke is 178 millimeters) is designed for an SS109 cartridge of the 5,56 caliber mm (NATO 5,56xXNNUMX).
On the basis of the machine gun "Heckler und Koch" they wanted to create a large-caliber single machine gun. The experimental model HK25 was made for the .50 “Browning” cartridge and had a tape feed. Despite all the improvements, his "bring" did not work.
Technical characteristics of the NK21Е / NK23 manual machine gun:
Cartridge - 7,62x51 / 5,56x45;
The weight of the machine gun with a bipod - 9,3 / 8,75 kg;
Machine gun length - 1140 / 1030 mm;
Barrel length - 560 / 450 mm;
The number of grooves - 4;
The length of the stroke rifling - 305 / 178 mm;
The rate of fire - 800 / 750 shots per minute;
The initial speed of the bullet - 840 / 950 m / s.