Gas piston

Discussion in 'AUG, MSAR' started by UziGeo, Aug 11, 2006.

  1. UziGeo

    UziGeo Guest

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    What exactly does the gas piston on the AUG or USR do? The FAL piston drives the operaitng rod back to cycle the bolt. The setting allows gas to excape due to the setting. When too much gas is exhausted, the gun will not cycle. When too much gas is kept in the system, it gives the bolt a hard knock against the back of the receiver. That will cycle the bolt, but will give more wear to the back of the receiver. Does the gas piston on the AUG/USR limit the gas so it will cycle the bolt? There is no operating rod on the AUG/USR. It must limit the gas pressure down to a point to where the bolt will unlock, Right? On the AR15, It cycles the bolt. On the AK47, although it doesn't have a gas piston, the gas pressure drives the [operating rod] to cycle the bolt also. There is no adjustment on this. Let's all jump in here and revive this forum! Uzi Geo. Thank's.
     
  2. irishsteyrfan

    irishsteyrfan New Member

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    AUG gas system -

    Gas Plug head has 3 settings/holes:
    1. Normal Fire - small bore hole
    2. Adverse - medium bore hole
    3. Grenade - large bore hole

    On the inside of the barrel there is a small bore hole that goes into the gas cylinder. The setting of the Gas Plug head determins how much gas gets into the cylinder.

    This gas, that enters the cylinder when a round passes via bore hole in barrel and gas plug head, forces the gas piston backwards. The gas piston then forces the right tube of the gun lock group to the rear. This rearward action moves the Lock Bolt's control pin and unlocks the locking lugs of the lock bolt from the locking lugs in the locking bush.

    :idea: i can finish off this brief if anyone wants more info. too tired to do it now!
     

  3. some_finn

    some_finn Guest

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    What do you mean there is no operating rod in the AUG? 8-O Of course there is.
    I think you're slightly confused what comes to the terms and the way the systems operate.
    The gas piston is the part on which the gas acts directly. There may or may not be an additional operating rod, depending on the system. You seem to be using both terms to describe the gas piston, depending on the rifle you're talking about, or something?

    The AUG system works exactly like the FAL system. The only difference is that the FAL doesn't have a separate gas piston and operating rod like the AUG has.
    The FAL only has the piston, the rear of which hits the bolt carrier to cycle the rifle. after the gas has hit the front of the piston. It has several gas settings as you mentioned.

    The AUG has a gas piston (the small thingy in the little gas tube on the side of the barrel) and an operating rod, attached to the bolt carrier. The bolt carrier has two rather similar rods. The one on the left is used in conjunction with the cocking handle to load the rifle.
    The gas hits the gas piston, which gives the operating rod a push to drive the bolt carrier back.
    The AUG gas system has three settings, one for normal conditions, another for adverse conditions/dirty weapon and a third one (totally closed) for firing rifle grenades, as mentioned.

    The AR-15 has neither a gas piston, nor an operating rod. The system is direct impingement, meaning that the gas is fed into the bolt carrier through the gas tube, and it drives the bolt carrier directly.

    The AK also has a gas piston, the biggest one of all the rifles mentioned here actually. It's attached to the bolt carrier and unlike in the FAL and AUG, the piston moves all the way back with the bolt carrier as the rifle cycles.

    The AR-15 and the AK have no gas adjustment, you've got that right.

    [​IMG]
     
  4. irishsteyrfan

    irishsteyrfan New Member

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    [​IMG]
     
  5. UziGeo

    UziGeo Guest

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    Thank's for all or your inputs! I guess I was slightly confused. I see that the gas piston does indeed line up with the operating rod on the right side. I had wondered why there was no fouling on that rod, but as I see it, the three gas rings prevent debris from flowing past it. It just drives the rod rearward. I am more familiar with the other rifles, and thought they were somehow similar. What a wonderful design! Great pic, also!