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to push it rearward and open it, the ejecting it farther back in its travels.
gas delayed blowback system directs The bolt’s/slide’s movement will also
those same gasses into a cylinder cock the hammer. On its forward
under the barrel that pushes forward, travel, the bolt/slide will strip a new
against a piston that forces the bolt/ round from the magazine and feed
slide closed. and seat it in the chamber. When the
bolt/slide bottoms out against the
During discharge, a small amount of
barrel, the chamber is fully closed.
gas is tapped from the bore just ahead
of the chamber. This gas is directed The gas delayed blowback action saw
down, into a cylinder under the barrel. moderate use during WWII with
One end of the cylinder is sealed by Germany and the Volkssturmgewehr
a piston that is attached to the bolt/ 1-5 rifle and the Grossfuss
slide. As the bullet travels through Sturmgewehr, both chambered in
the bore, the cylinder becomes fully 7.92x33 Kurz. The design was later
pressurized and the same gas begins picked up by Heckler & Koch (P7),
to push against the case and the bolt/ Walther (CCP), and Steyr (GB). The
slide face. The bolt/slide is stopped by delayed-blowback action has been
the piston acting against the pressur- typically reserved for pistol caliber
ized cylinder. When the bullet exits cartridges even though it has been
the muzzle and the gasses are allowed employed by pistols and rifles.
to escape, the cylinder will depressur-
› Chamber-Ring delayed – The
ize and the inertia in the bolt/slide
chamber-ring delayed blowback ac-
will overcome the action/recoil spring
tion is by far one of the simplest
and move rearward.
means of slowing the chamber’s open-
On its rearward travel, the bolt/ ing. Unlike the other systems that
slide will pull the empty case with it, rely on external, mechanical means
extracting it from the chamber and to slow the chamber’s opening, the
Figure 8: Chamber-ring delayed action.
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