Think of it this way,

As soon as the bullet passes the barrel gas port, the gas action is pressurized, the carrier starts to be pressurized back, with the bolt starting to rotate in the barrel extension via the carrier cam.  The spent case is still bound to the chamber wall due to bore pressure, so until the bolt can rotate around (being cam'd around as the carrier comes back) to allow the bolt lugs to unlock from the barrel extension lugs,  extractor is just slipping around on the spent case rim.

Now by the time the bolt does unlock from the barrel extension and the bolt can come back/ extractor pulling the spent cases out of the chamber, the residual pressure in the barrel bore that is pressure binding the spent case to the chamber walls has dropped to a level that the spent case can be pulled cleanly.

So the extractor is always over the rim of the case, but until the bolt unlocks from the barrel extension, the extractor is not pulling on the spent case yet.

Furthermore, since barrel residual pressure has to drop down enough that the extractor can pull the pressure bound spent case from the chamber, a bolt/rifle that is unlocking too fast, will short stroke as well. Not enough gas to the system, and the B/C does not have the correct energy to get the B/C all the way back.  Too much gas,and although the B/C has energy, the spent case is still too pressure bound to be pulled from the chamber, that energy is lost trying to pull the too pressure bound case.

Simply, the key thing about this topic is to see that although the working pressure of most rounds are in the 55K range, there is a drop in pressure after the peak dwell of the burn, which means that the gas action does not see 55K of working pressure. To take is one step farther since I refer back to this topic regarding gun powder burn rate, the slower the powder burns to achieve the working pressure of 55K, the higher of pressure that both the gas action will receiver, and the higher of the residual pressure of the spent case pressure bound to the chamber wall at the pull.

Think drop in residual bore pressure (spent case pressure welded to the chamber walls) for the spent case to be pulled from the chamber walls more easily.


Also the closer the gas port is to the chamber, and the less there is of bore after the gas port, the more that the rig is going to ammo sensitive.

This is mostly   about 20" barrels, but :: https://www.ar15.com/archive/topic.html?b=3&f=121&t=673071





http://www.practicalmachinist.com/vb/gunsmithing/gas-port-sizes-308-style-ars-188690



CHART
 

ZQI ammo is turkey nato ammo, and is Nato hot.

So if the rig is choking on the ammo (short stroking due to what seems to be over fuction) , then suspect that you need to spend more time chamber brush cleaning the chamber to get it clean, as well as using cleaning solvent that will not leave behind a sticky resude.

So for starters, make sure that you are only using something like Sweets copper solvent to clean the bore rifling, and then CLP to clean (including scrubbing the chamber with CLP and a 308 AR chamber brush), then lubing the upper bearing areas with CLP as well.

Also, you say that it a AR-10, but is this really a Armalite rig (both barrel and bolt being Armalite, and not one them being a Stoner/DPMS part instead).   If a DPMS, then tend to chamber (side wall demension) on the tigher side to promote accuracy, and with the tighter side wall chamber, less blow by at brass firing forming to cause higher working pressures with the ammo isntead.  So the DPMS rigs will run fine with most 308 ammo, but when you step up to 7.62 nato ammo, it can cause some problems until the chamber has been polished out via live fire isntead.

If you want to go into more detail about the rifle and the problems is having with the Turkey Nato ammo, then start a new thread in trouble shooting isntead. Hence it's not due to a gas port problem, but a tight chamber problem instead.