PK Series Manual (English, 2005) - Forgotten Weapons

Slide and Piston Assembly. The slide and piston assembly serves to house the bolt,
extract cartridges from the link belt, lock the bolt from below when it is in the forward
position, absorb the force of the propellant gases, unlock the bolt, and return it to the
rear position, as well as to cock the trigger mechanism. The slide with piston (see figure
1-27) consists of the frame, piston, and the cartridge extractor.
Figure 1-27. Slide & Piston Assembly
Frame. The frame has a hole in the back for the driving spring, a lug with a hole for the
pin of the cartridge extractor, and a hole for the bolt body. On the interior surface of the
hole for the bolt body there is a semicircular groove for guiding the lug of the firing pin
during locking and unlocking.
On the sides of the slide frame there are grooves that guide the motion of the slide
frame along the curved sides of the receiver. The right groove has a further slot in it
which allows passage of the ejector. On the top of the lug of the slide frame is a lateral
groove with two teeth which holds the cartridge extractor. On the upper rear, in front of
the extractor lug, there is a spiraled groove for the profiled lug of the bolt. On the left
side of the spiraled groove is a beveled lug onto which the beveled face of the profiled
lug of the bolt fits. On the bottom of the slide frame there is a cutout lug which is held by
the sear tooth when the slide is in the rear position and the trigger is not pulled. On the
sides of the frame grooves have been cut out for guiding the feed pawl. On the right
side of the frame is a lug which the cocking lever tooth catches. On the front of the
frame are profiled lugs for attaching the piston.
Piston. The piston serves to absorb the pressure of the propellant gases and transfer it
to the slide frame. The rear of the piston has a shoulder which fits into the profiled lugs
of the slide. The slide and piston are joined by a pin. On the front of the piston there are
rings and grooves for sealing the gas block. The rear or guide ring guides the motion of
the piston in the gas cylinder.
The cartridge extractor fits onto the lug on the slide frame and is fastened with a pin.
Its bottom has a profiled lug, and its top has two claws with a vertical slot for
catching the cartridge case rim.
UNCLASSIFIED
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