B-51 rail is designed for PK, PKM and PKP machine guns. It is a milled product made of aluminium alloy D16T coated by black or desert color.
B-51 is installed on the receiver of Kalashnikov machine gun by replacing the standard hinge to the hinge from the kit.
The installed B-51 rail forms a Picatinny rail with a length of 19 numbered units above the receiver, which does not cross the aiming line when using standard iron sight.

Specifications:
Material: D16T aluminum alloy
Weight: 225 ± 5 g
Overall dimensions: (257x59x62) ± 5 mm
Working range of ambient temperatures: from -50 ° С to + 50 ° С

In the kit:

B-51 rail	1 pc.
Hex key	1 pc.
Hinge (longer - for B-51, shorter - as a replacement of a standard hinge)	2 pcs.
Hinge punch	1 pc.
Washers	2 pcs.
Cotter pin	2 pcs.
Manual	1 pc.

To install B-51 on the machine gun:

1. Install the supplied hinge punch on the left side of the receiver against the standard hinge of the receiver cover perpendicular to the axis of the weapon and parallel to the floor, carefully hammer out the standard hinge. The hinge punch should take the place of the regular hinge. Do not open the dust cover! Do not hammer out the regular hinge without the hinge punch!
   
2. Install B-51 rail over the receiver so that the stops in its rear part are located at the bottom of the rear sight cover, and the side holes located on the left and right of the front of the B-51 rail are aligned with the hole in which the punch has already been installed.
   
3. Install the hinge from the kit (longer one) on the left side of the receiver into the side hole of the B-51 bracket so that it is perpendicular to the weapon axis and parallel to the floor, carefully using a hammer to dismantle the punch previously installed to replace the standard axis with a hammer receiver cover
4. Install a washer on the hinge, and a cotter pin in the hinge hole, and unpin it
5. Tighten the screw that pushes the bracket off the receiver cover
   

ATTENTION!!! All screws in the B-51 rail have a right-hand (standard) thread. To avoid product failure, tighten and unscrew the screws very carefully, completely inserting the key into the screw.

More detailed illustrated instructions are in the instruction manual.