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I tend to believe that gas port erosion happens and moving the port farther forward is a good thing.
Last edited by cacop; 03-27-11 at 00:52.
Somewhat of a semantic argument, it actually is a regulator. Any air regulator is just a needle that opens and closes into a tapered orifice changing the size of the opening. A gas port just happens to be a fixed size. A smaller gas port will have a higher pressure right at the gas port (gasses compress so pascal's principle doesn't apply.) but it will restrict volumetric flow, thus requiring more time before peak pressure is reached. Opening up the gas port results in less pressure, again, right at the gas port, but peak pressure will be reached faster.
Any carbine requires a specific amount of internal pressure to begin unlocking and as long as the bullet is still in the barrel and the bolt is locked, pressure continues to build. In the case of a carbine, pressure is a function of volume and temperature. Volume is a function of gas port size. The gas port is sized to allow enough volume of gas into the bcg to generate necessary unlocking pressure at the proper time.
Last edited by Eric D.; 03-27-11 at 01:12.
B.A.S. Mechanical Engineering Technology
The gas port isn't a regulator, it's a restrictor. A regulator regulates a higher pressure from one side to a lower pressure on the other. When the system is fully charged, the low pressure side will not exceed the pressure set by the regulator although the pressure on the high side is higher.
A restrictor doesn't reduce the PSI, it simply controls how fast the gas will pass through. When a system with a restrictor is fully charged, the pressure will be equal on both sides
INSIDE PLAN OF BOX
- ROAD-RUNNER LIFTS GLASS OF WATER- PULLING UP MATCH
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Zomg it's an orfice plate. >.>
I am not expert on gas port sizes but this is where my comment about making it smaller comes from.
Colt uses a .061-062 sized gas port on their 6920 that comes standard with a 16" barrel.
Colt uses a .070 gas port on their MK18 with a 10.5" barrel.
These two things lead me to believe that a shorter barreled rifle needs a larger gas port than a longer barrel to function.
There are a few posts on this board with guys running SBR's with gas ports in the high .050's that function reliably. And that is without a suppressor installed.
This makes me think that .061 might not be the smallest port size a 14.5-16" barrel needs to operate.
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