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Durkin Tactical Franklin Armory
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Posted: 4/16/2001 7:48:06 AM EDT
I am looking for some information on how the ar15 actually works, more specifically how the direct gas action actually functions.  If someone could tell me, or point me to a website I would appreciate it.  Thanks.
Link Posted: 4/16/2001 7:53:11 AM EDT
Link Posted: 4/16/2001 9:15:36 AM EDT
I will be on the look out for it, thanks.
Link Posted: 4/16/2001 9:31:53 AM EDT
The pressurized gas is tapped off from the barrel and piped back into the bolt carrier.  The gas is exhausted into the carrier between the gas rings (attached to the bolt) and the back wall of the bolt channel within the carrier.  The high pressure gases act to push these surfaces apart.  Since the bolt is rigidly locked within the barrel extension, it cannot move, and instead the bolt carrier is pushed back.  As soon as the carrier has moved back a few millimeters, the gas rings pass the little holes drilled in the right side of the carrier, and the gas is exhausted to atmosphere through the ejection port, but by that time the carrier has picked up enough momentum that it will run all the way to the back of its travel, unlocking and taking the bolt with it.

Originally Posted By Darin Marple:
I am looking for some information on how the ar15 actually works, more specifically how the direct gas action actually functions.  
Link Posted: 4/16/2001 10:51:28 AM EDT
Thanks for the description.  This was what I was looking for.  

So the operating principle is the same as a AK except without a piston.  The expanding force of the gas against the locked bolt operates the carrier instead of a expanding gas driving a piston which in turn drives the carrier.  Interesting...

One thing I do not understand is how the bolt actually locks, can you tell me how this works?

Link Posted: 4/16/2001 11:03:18 AM EDT
Link Posted: 4/16/2001 1:13:00 PM EDT
Link Posted: 4/16/2001 3:30:21 PM EDT
Link Posted: 4/16/2001 4:58:20 PM EDT
The short name for the theory is "FM."
Link Posted: 4/17/2001 7:40:27 AM EDT
Exactly what I was looking for, thank you.
Link Posted: 4/17/2001 7:52:40 AM EDT
It's not the same as a piston only type action.  The key to the Stoner system and what realy sets it apart from others is that the gas flows into a chamber that pushes the bolt forward (trys to anyway) and the bolt carrier backward.  This adds greatly to the positive opening, extraction, ejection procedure and reduces stress on those components that normaly see the most stress and ware, namely the bolt lugs and barrel extension lugs.  There is no metal on metal slamming together.
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