Known 7.62 mm AK-47 Kalashnikov assault rifle (see Manual on firing, 7.62 mm AK Kalashnikov assault rifle, M. DOSAAF Publishing House, 1969) has a receiver, a barrel with cartridge chamber and a rifled part, a bolt support with a bolt, a trigger and firing mechanism with a firing trigger, firing hammer and autosafety and an unfolding butt.

Known 7.62 mm improved AKMS Kalashnikov assault rifle with folding butt (see Manual on firing. 7.62 mm AKM and AKMS Kalashnikov assault rifle. M. Military Publishing House of the Ministry of Defence of the USSR, 1971) taken as the prototype features a receiver, a breech locking mechanism containing a turning bolt with a firing rod placed in the bolt support installed on rails of the receiver and having a rear lug interacting with the firing hammer, a trigger and firing mechanism containing a hammer and a sear of autosafety, a gas-escape mechanism with a gas piston the rod of which is installed in the hole of the bolt support, a folding butt and a barrel with a rear-sight bed comprising a cartridge chamber and a rifled portion.

The shortcomings of this model are low reliability, failure of the rifle when it is used in extreme climatic and non-standard conditions, relatively low accuracy of fire, insufficient operational characteristics.

The object of the claimed invention is to increase reliability and operational characteristics of the rifle.

To solve the problem the assault rifle features a receiver, a breech locking mechanism comprising a turning bolt with a firing pin placed in the bolt support installe on rails of the receiver and having a rear lug interacting with the firing hammer, the trigger and firing lock comprising a hammer and a sear of autosafety with sear notch, a gas-escape mechanism with a gas tube and a piston the rod of which is installed in the hole of the bolt support, a folding butt with retainers of firing and stowed positions and a barrel with a rear-sight bed comprising a cartridge chamber and a rifled portion.

The novelty of the claimed device is that the bolt support is made in such a way that it can interact in the front position with the tapered supporting surface of the receiver; the rear lug of the bolt support has such length which prevents contact of the firing hammer with the firing pin when the bolt support recoils; the rod is placed in the bolt support in such a way that it allows for limited angular displacement, and the gas tube is equipped with a lug contacting the slot of the rear sight bed.

The rod of the gas piston is inserted into the hole of the bolt support with the help of threading with clearance. The sear of autosafety is equipped with a sear notch of hand reloading in the form of a platform on the sear placed at a distance from the path of the bolt support providing contact of the bolt support with the firing hammer; the platform of the automatic sear notch of the sear is made at a distance from the path of the bolt support providing a clearance between the bolt support and the firing hammer.

Inside the butt there are reinforcing ribs which form a trap for accessory box which is closed by a spring-loaded turning cap installed in such a way that interaction of the pusher and the retainer of the stowed position is allowed.

The gas escape tube is spring-loaded with respect to the rear-sight bed in the direction of the muzzle end.

In the rifled portion of the barrel transition from the rifling land to the bottom of groove is made in the form of two adjoining radii and a tangent located perpendicularly to the plane passing through the bore line and the centre of the rifling land. In the barrel between the conic taper of lands and the rifled portion an additional conic section is made with the length of LL = (4... 6) L, where L is the sum of the lengths of support cone of the cartridge chamber and conic taper of the lands.

Combination of the proposed features of the claimed automatic weapon has considerably increased reliability and operational characteristics of the unit.

The essence of the invention is illustrated by the following drawings: Fig. 1 General view of the assault rifle; Fig. 2 View A in Fig. 1, the bolt support in the front position in contact with the lug of the receiver; Fig. 3 gas-escape mechanism; Fig. 4 cross-sectional view G-G in Fig. 3; Fig. 5 firing hammer in contact with the rear lug; Fig. 6 firing hammer on the sear notch of the hand reloading of the automatic sear; Fig. 7 firing hammer on the automatic sear notch of the automatic sear; Fig. 8 plastic butt with the receiver (cross-section); Fig. 9 butt, cross-section B-B in Fig. 8; Fig. 10 butt, cross-section P-P in Fig. 8; Fig. 11 butt, magnification D in Fig. 8; Fig. 12 barrel (cross-section); Fig. 13 side view of the rifling in the barrel, cross-section E-E in Fig. 12; Fig. 14 note in Fig. 13; and Fig. 15 note M in Fig. 3.

The claimed automatic weapon (Fig. 1) contains a receiver 1 to which the barrel 2 is attached at the front and a folding plastic butt 3 at the back. On the barrel a rear-sight bed 4 and a gas chamber 5 are installe; between them a gas tube 6 is placed. In the receiver (Fig. 4) on rails 7 the breech locking mechanism is installed (Fig. 3) comprising a turning bolt 8 with a firing pin 9 placed in the bolt support 10. The bolt support has a rear lug 11; in the hole of the bolt support a rod 12 with a piston 13 is fixed with the help of threading with clearance. At the side the bolt support has a tapered supporting platform 14 (Fig. 2), on the receiver a lug 15 with a reciprocal tapered platform 16 is made. The gas tube has a lug 17 down at the back which fits into the slot 18 of the rear-sight bed 4 and is spring- loaded by spring 19 in the direction of the muzzle end. Inside the receiver a trigger and firing mechanism is placed (Fig. 6) containing a firing hammer 20 and an autosafety with a sear 21 featuring hand reloading sear notch in the form of a platform 22 and an automatic sear notch in the form of a platform 23 (Fig. 7). To the receiver 1 (Figs. 8,9) with the help of an axle 24 the butt 3 is fixed on a hinge. It comprises a hollow plastic case 25, a buttplate 26, a pusher 27 with a lug 28 which contacts the retainer of the stowed position 29. Inside the butt case reinforcing ribs 30 (Fig. 10) are made which form a trap 31 for the box 32 with accessories. The box is spring-loaded by a spring 33 and rests against a turning cap 34 the lower lug 35 (Fig. 11) of which contacts the reciprocal lug 36 of the pusher 27.

The side recess 37 (Fig. 9) on the outer surface of the butt is made in the form of a seat to house the night-sight leaf 38 fixed on the receiver 1. In the rear part of the receiver a spring-loaded f'-shaped retainer of the firing position of the butt is placed.

The barrel 2 of the rifle (Fig. 12) comprises a cartridge chamber 40 with a supporting cone 41 and a rifled portion comprising a land conic taper 42, an additional conic area 43 and a cylinder portion 44. The length of the additional conic area is LL = (4... 6). (Ls + Lc), where Ls is the length of the supporting cone and Lc is the length of the conic taper of lands.

The rifled portion of the barrel is a profile with rifling and lands (Figs. 13, 14). Transition between them comprises"ab"portion with the radius r, "bc"portion with the radius r2 and"cd"portion which is tangent n to radius r2 which is normal to surface S passing through the bore axis and the centre of the land; d, is the land diameter and dR is the rifling diameter.

The automatic weapon operates in the following manner. To load the rifle it is necessary to pull the bolt support 10 backwards and release it abruptly. When the bolt support is pulled backward ist rear lug 11 cocks the hammer 20 which engages the sear notch of hand reloading 22 of the sear 21 of autosafety at a distance from the path of the bolt support which results in interference K between the hammer and the bolt support.

When the firing trigger is pressed a shot takes place and powder gases actuate the bolt support via the piston 13 with the rod 12 and throw it back. During the backward movement the bolt support cocks the hammer again; the hammer turns and engages the sear notch 23 located at a distance from the path of the bolt support forming a clearance L between the hammer and the bolt support. Due to that, when the bolt support counterrecoils it passes over the hammer freely without touching it which provides for higher reliability of operation. When the hammer is cocked by the rear lug 11 it never contacts the firing pin 9 because a clearance, N" (Fig. 5) is provided due to specially selected length, and the firing pin does not push the cartridge from the cartridge case seat before the due time which eliminates loss of the cartridge.

When the bolt support 10 takes the front position its supporting platform 14 tapered under the angle (Fig. 2) strikes the reciprocal tapered platform 16 of the lug 15 of the receiver. In this process the bolt support moves to the left and presses itself to the left rail 7 of the receiver. The piston 13 of the rod 12 of the bolt support enters the gas chamber 5 and taking up the clearance in the threaded joint with the bolt support turns at the proper angle compensating for errors in the gas chamber installation on the barrel and eliminating the skewness of the bolt support.

In the process of shooting the gas tube 6 fixed by the log 17 in the slot 18 and spring-loaded by the spring 19 of the rear-sight bed 4 does not make any inertial movements.

In the process of shooting the bullet cuts into the rifle lands at the initial moment; the additional conic area 43 promotes a smoother, more uniform cutting-in of the bullet reducing the specific pressure of the bullet on the lands. All that promotes smoother defomation of the bullet according to the form of the lands and increases the service life of the barrel.

Availability of the curved transition surface from the lands to the rifling "abc"formed by radii r1 and r2, and a linear section cd"along the tangent allows for better filing the rifling by the bullet jacket thus preventing powder gas leakage and increasing stability of the bullet muzzle velocity.

The plastic butt 3 can be folded from firing position to stowed position and vice versa. To put the butt from the firing position to the stowed position one should press the pusher 27 protruding from the hole of the buttplate 26; the pusher 27 moves in the cavity of the butt case 25 and by its lug 28 acutates the retainer 29 of the stowed position and releases the retainer form gear with the side wall of the buttplate 26. After that one should turn the butt around the axle 24 and put it into the firing position.

To put the butt into the stowed position one should press the retainer of the firing position 39 and turning the butt around the axle 24 put it into the stowed position. As the result of this the retainer 29 of the stowed position engages the side edge of the buttplate 26 and by its tooth fixes the butt in the stowed position. When the butt is folded the night-sight leaf 38 is placed into the pocket 37 on the outer surface of the butt. To withdraw the box 32 with accessories one should energetically press the cap 34 of the buttplate 26 with a finger; the cap will turn and open the hole in the buttplate. Thanks to the spring 33 the box will withdraw from the hole formed by the reinforcing ribs 30 in the cavity of the butte case 25. The spring-loaded cap 34 will turn back to the initial position; to do this the lower lug 35 of the cap interacting with the lug 36 of the pusher 27 will move the pusher to the backward position.

The claimed invention completely solves the aimed technical problem: increase of reliability and operation characteristics, and it will be widely spread in new models of"Kalashnikov Assault Rifle"design manufactured at present (AK 101, AK 102, AK 103, AK 104, AK 105 etc.).