Example
Subsonic ammunition - have less pressure and needs a large gas port to fill the same volume of gas to create enough pressure to operate
Standard ammunition - have more pressure and needs a smaller gas port to fill same volume of gas to operate
So in ideal conditions the volumes of gas would be the same for both subsonic and standard ammunition. But the size of the port would increase or decrease.

There is normally a misconception that it is the quantity of gas that allows a system to operate. Example certain ammunition needs more gas to operate - it actual needs a large gas port to send the same volume of gas down the system.


Please give your opinions or inputs regarding this statement.