1 - bolt support; 2 - firing pin; 3 - cover; 4- guiding rod; 5 -guiding bushing; 6 - bolt; 7 - extractor pin; 8 - firing pin stud; 9 -extractor spring; 10 - extractor; 11 - return spring; 12 - sight leaf slide; 13 - sight leaf; 14 - hand guard, L.H. ; 15 - pusher spring; 16
- gas tube latch; 17 - gas chamber; 18 - gas piston; 19 - gas tube 6B1; 20 - gas regulator; 21 - front sight body; 22 - front; 23 - pusher; 24
- front sight base; 25 - barrel; 26 - upper band, assembly; 27 - band axle pin; 28 - oil seal, assembly; 29 - hand guard, R. H. ; 30 - upper band with spring; 31 - magazine body, assembly; 32 - magazine spring; 33 - magazine cover; 34 - sight leaf, assembly; 35 - follower; 36 -receiver; 37 - accidental shot safety device; 38 - firing and trigger mechanism; 39 - cover axle pin; 40 - butt assembly.
1.4.1. The sniper rifle consists of the following main parts and mechanisms (Fig. 2):
barrel with receiver; bolt with bolt support; safety lever, assembly; firing and trigger mechanism; cover with retracting mechanism; magazine; butt;
upper band, assembly; hand guard, L.H., assembly; hand guard, R.H., assembly; sight leaf, assembly;
front-sight base and body, assembly.
1.4.2. The sniper rifle is a self-loading weapon. The reloading of the rifle is based on utilizing the energy of powder gases which arc channeled from the barrel bore to the gas piston.
Upon firing, a certain amount of the powder gases following the bullet flows through the port in the barrel bore wall into the gas chamber, exerts pressure upon the front wall of the gas piston and throws back the piston with pusher and, consequently, the bolt support into the rearward position.
As the bolt support travels rearward, the bolt opens the barrel bore, the cartridge case gets removed from the cartridge chamber and ejected out of the receiver. The bolt support compresses the return springs and cocks the hammer; i. e. engages it with the auto-safety cocking cam.
The bolt support and the bolt return to the front position under the action of the retracting mechanism; as a result, the bolt feeds the next cartridge from the magazine into the cartridge chamber and closes the barrel bore, while the bolt support disengages the auto-safety sear from the hammer. The hammer gets cocked. The bolt gets locked, after it has been turned to the left and its locking lugs engaged with recesses of the receiver.
To fire a shot, it is necessary to release the trigger and press it anew. After the trigger has been released, the rod moves forward and its hook engages the sear and, if pressed, the rod hook turns the sear and disengages it from the hammer-cocking cam.
The hammer actuated by the mainspring turns round its pin and strikes the firing pin. The latter travels forward and impinges the primer. Thus, a shot is fired.
With the last cartridge fired and the bolt returned to the rearward position, the magazine follower lifts the bolt catch; the latter engages the bolt to stop the bolt support in the rearward position. Thus, it is necessary to load the rifle anew.
The rifle has a gas regulator, which serves to change recoil speeds of moving parts. Under conditions of proper servicing with the parts lubricated, the gas regulator is set at division 1. On firing during a long time without cleaning and lubricating and heavy soiling of the rifle, stoppage may occur s incomplete recoil of the moving parts. In this case the regulator is set at division 2. To change the regulator from one position to another use the rim of the cartridge case or the cartridge.
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