How the St.G44 weapons work
When the trigger is pressed the hammer is released to strike the inertia firing pin. This is a wedge-shaped pin which does not have a conventional spring. It is primer retracted.
As the bullet passes the gas port in the barrel it expands into the gas chamber or cup which is screwed into the housing around the barrel and on top of it.
The gas impinges on a piston somewhat resembling the old Lewis piston and drives it to th rear. In the start of its rearward travel, the piston (which is attached to it by a fixed pin the bolt carrier) can move without interfering with the secure locking of the weapon. A gas went in the top of the casing permits the gas to escape as the gas end in the piston clears it.
After a short rearward travel the bolt carrier hook picks up the separate bolt member, mounted below it, and pulls it down and back to perform the unlocking action.
The recoil spring is mounted behind the bolt extending back to the stock. This spring is compressed as the moving members travel to the rear to extrack and eject the empty case in normal fashion and to cock the hammer.
This weapon is fitted with a disconnecter.
How the AK works
Full automatic fire. With the safety selector set on full automatic fire, a cartridge in the chamber (to chamber a cartridge initially, since the AK fires from a closed bolt, it is necessary to pull the operating handle to the rear and release it), and a loaded magazine in the weapon, the following occurs when the trigger is pulled. The safety selector lug is far enough to the rear to release the rear of the trigger, but stays directly above the rear end of the disconnector. Thus, while the trigger is free to rotate, the safety selector lug prevents the disconnector from rotating. One large multi-stranded spring is used as both hammer spring and trigger spring in the AK. [note: this is more like the MP-40, actually, but also a lot like the PPSh 41. This was two springs on the St.G. 44]
Semiautomatic fire To fire a single round from the rifle, set the weapon for semiautomatic fire by rotating the safety selector as far down as possible, and then press the trigger.
When the trigger is pressed, the semiautomatic sear and disconnector rotate. The rear end of the sear (which is actually a part of the trigger) raises the ends of the hammer-and-trigger spring. As the trigger rotates, the semiautomatic sear releases the hammer cock notch.
The hammer-and-trigger spring rotates the hammer forward, and the hammer strikes the rear and of the firing pin, pushing it forward so that it strikes the primer of the cartridge. The cartridge fires, and gasses from the cartridge flows through the gas port in the barrel into the gas cylinder and force the piston and bolt carrier assembly move to the rear, the recoil spring is compressed. The bevel in the bolt carrier cam acts on the bolt guide lug, rotating the bolt to the left and thereby unlocking the bolt.
After the bolt is unlocked, the bolt carrier and bolt move to the rear together. The bolt carrier rotates the hammer to the rear, compressing the hammer-and-trigger spring. As the hammer rotates, it rotates the disconnector, the disconnector spring forces the disconnector to engage the disconnector notch in the hammer. This holds the hammer at full cock.
The full automatic sear spring rotates the full automatic sear into engagement with the full automatic sear notch in the hammer. The full automatic sear, however, does not hold the hammer in the cocked position, since the disconnector is already performing this function. As the full automatic sear rotates, the upper and of the sear rises to obstruct the passage of the full automatic disconnector.
As the bolt moves to the rear, the extractor pulls the cartridge case from the chamber. When the case strikes the ejector, it is ejected from the receiver.
The top round in the magazine is forced upward by the follower until it is arrested by the magazine flange.
The rearward movement of the bolt carrier and the bolt is arrested by the rear wall of the receiver Forward movement of these parts are caused by the decompression of the recoil spring.
As the bolt carrier moves forward, the top cartridge in the magazine is stripped from the magazine and forced into the chamber.
As the bolt approaches the barrel face, the first stage in the rotation of the bolt to the right takes place. At the same time, the extractor engages the extractor groove of the cartridge case. As the bolt carrier moves to the extreme forward position, it produces the final rotation of the bolt to the right, locking the bolt.
After the bolt is locked, but while the bolt carrier is still a short distance from the extreme forward position, the full automatic disconnector (which is integral with the bolt carrier) strikes the upper end of the full automatic sear, and rotates the sear forward. This action moves the full automatic sear away from the hammer, so that the hammer will not be prevented from firing.
The next round is fired by releasing the trigger, and then pressing it again. When the trigger is released, the hammer-and-trigger spring rotates the disconnector and semi-automatic sear to the sear, disengaging the disconnector from the disconnector notch in the hammer. The trigger-and-hammer spring rotates the hammer until the hammer cock notch engages the semi-automatic sear. This is accompanied by an audible click.
When the trigger is again pressed, the semiautomatic sear releases the hammer cock notch. The hammer once again strikes the firing pin, and the entire operating cycle of the automatic mechanism is repeated.
Automatic fire To fire the rifle automatically, set the selector at full automatic fire by rotating the indicator until it is opposite the Cyrillic letters AB on the receiver, and press the trigger.
When the trigger is pressed, it rotates the trigger pin. The disconnector, because it is prevented from rotating by the selector lever, does not engage the disconnector notch in the hammer.
As the trigger rotates, the semiautomatic sear releases the hammer cock notch. The hammer-and-trigger spring rotates the hammer, which strikes the firing pin forcibly. The round is fired. The powder gasses act on the gas piston, thrusting the operating rod to the rear, opening the bolt, extracting and ejecting the cartridge case, and cocking the hammer.
The full automatic sear engages the full automatic sear notch in the hammer, holding the hammer at full cock.
The top round in the magazine is raised by the follower.
As the bolt carrier and the bolt are moved forward by the recoil spring, the round is fed into the chamber and the bolt is locked.
When the bolt carrier is a short distance from the extreme forward position, the full automatic disconnector strikes the upper end of the full automatic sear and rotates the sear, releasing the hammer. The hammer strikes the firing pin, firing the next round.