Adjustable gas blocks are designed to do none of those things.
They are for using suppressors. They are also for precision shooting so you can dial in the pressure for whatever type of ammo you want to use.
The gun advice on FR is getting ridiculous.
3 gun competition users also use them for faster follow up shots. Winning and losing can be separated by fractions of seconds at high levels.
You are correct that their biggest advantage is for suppressors.
yep, suppressors change things.
Post No. 5 by manly warrior is the only input so far that has any merit. The facts are:
1. No device that does not decrease projectile velocity can reduce recoil. Sir Isaac Newton settled that issue eons ago with his famous Conservation of Momentum equation of M1V1=M2V2.
2. Adjustable gas blocks serve a purpose unrelated to Suppressor functioning or effectiveness.
3. Adjustable gas blocks are used primarily to throttle the impinging combustion gas with some ammunition loadings back to the point where premature extraction(PE) does not occur. That can damage the shellcase rim to the point of the extractor tearing off a portion of the rim and leaving the remaining shellcase stuck in the chamber.
4. PE is caused by both the gas pressure and gas volume released into the Gas Tube.
5. The gas pressure and gas volume are a function of three factors.
a) Location of the Gas Port. The closer to the chamber, the higher the pressure. That also affects the timing of when shellcase extraction begins.
b) The size of the Gas Port. Self explanatory.
c) How much barrel exists ahead of the gas port. That determines the amount of time the combustion gas has to enter the Gas Tube. Carbine length barrels have considerably more length ahead of the Port and therefor more time for the combustion gas to impart excessive velocity to the Bolt Carrier Group.
Back to Newton's Conservation Equation, PE can also be moderated by increasing the mass (weight) of the entire Bolt Carrier system, including the Buffer. Heavier Buffers and/or Bolt Carriers will decrease the velocity of the Bolt Carrier group and minimize PE and long term gun damage.
A heavier Recoil Spring can also slow down the Bolt Carrier Group.
You can determine the amount of PE your gun produces by examining the underside of the rim on fired shellcases. If the Extractor has left an impression, you have some degree of PE. That can be fixed as described above. Or you can use the type of ammunition for which your gun was designed.