
Originally Posted by
MistWolf
The rifle length uses a larger port size which allows the system to pressurize faster. Since the system pressurizes faster, combined with a longer distance to travel, isn't it possible that the cyclic rate of a rifle length would be the same as the carbine or the middy?
No, because the dwell time is far less in proportion to the volume of gas being sent through the tube. In addition, the gas being tapped at a rifle gas port is going to be at a lower pressure than at the CAR position.
The gas port regulates flow. The smaller port of the carbine system reduces the volume per second* the gases flow into the system. That means the volume flow of higher pressure gas (which is denser) will be about the same as the volume flow through the larger rifle port with it's lower pressure gas. This regulates cyclic rate. When the cyclic rate is kept within the specified range, stress on the BCG should be the same as the acceleration rate of the BCG will be about the same.
*Gas volume varies with pressure. One pound of air takes up less volume at 25,000 psi than it does at 15,000 psi. What the gas port of the AR really does is ensure the correct mass of gas at the right pressure is tapped into the system at the proper rate for the pressure being tapped.
I am not sure what you mean by the dwell time being less in proportion to the volume of the gas being sent through the tube.
I do think that the carbine system, due to tapping gases at a higher pressure point, is less forgiving, that the gas port diameter must be more precise for consistent operation. I also accept that my conclusions are suppositions until data can be collected and analyzed. However, my suppositions are based on the application of physics. That's why I'd like to see the math (which I admit to being wholly inadequate to apply) and/or actual collected data to analyze in order to test those conclusions
Bookmarks