PK Series Manual (English, 2005) - Forgotten Weapons

Figure 1-22. Gas Block Assembly
The gas block assembly slips onto the barrel and is fastened with two pins. On the
bottom in the elbow joint of the block there is a hole which allows the passage of the
propellant gases from the barrel. The front ring has a vent for the escape of excess
propellant gases. The rear ring has three round cutouts and a round groove. The arms
of the gas regulator fit into the cutouts and groove. The round cutouts are marked “1”,
“2” and “3”, and indicate the three positions of the gas regulator on the gas block.
Position “1” is used after 3000 rounds have been fired from the machinegun and is the
basic position of the gas regulator. Position “2” is used in case the slide does not return
fully to the rear position, and position “3” is used when the machinegun is fired in
adverse conditions (low temperature, rain, when the machinegun is dirty from propellant
gas products, etc.) and during the first 3000 rounds. The rear section of the gas block
fits into the gas cylinder.
Gas Regulator. The gas regulator (see figure 1-23) has two vents on the sides: on the
left side there is an elongated opening, and on the right side there is a round hole. The
openings serve to release the propellant gases from the gas port. When the regulator is
in position “1” both vents are open; in position “2” only the left vent of the gas block is
open; in position “3” both vents are closed. There are two rectangular lugs on the sides
of the gas regulator which facilitate its being switched from position to position. The gas
regulator arms fasten it to the gas block. On the ends of the arms are small studs that fit
into the round cutouts and round groove on the gas block. On the bottom of the
regulator there is a profiled lug with a groove in which the rim of a cartridge case fits.
The cartridge case and groove are used to adjust the regulator from position to position
when this cannot be done with the fingers (see figure 1-24).
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