They probably do not all work exactly the same, but whether this is by design or coincidence I have no idea. There are two "indentations" machined into the upper where the ejection port cover locks closed. My LR G2 Bull, right now in front of me, will often crack open only to the second indentation when the charging handle is pulled rearward. If I slowly lower the charging handle to full closed it will sometimes stay there and sometimes pop all the way. If I let the charging handle go when there is still spring tension, it will almost always pop all the way open when bolt slams forward, even if only the last inch of travel. Additionally, if I pull the charging handle back quickly, the cover will usually pop open all the way because it pops right past the second notch in the upper. It does appear that the second notch is supposed to be for ease of closing, just like any typical AR platform. Looking closely, I would say it is getting hung up between the indentations instead if in the second one. After a few more cycles and brake-in, this will likely start to open all way every time the charging handle is moved back.
I checked my notes on velocity. Box stock Federal 168 Gold Medal Match ammo averaged 2642 fps, while reloaded 175 SMK with 43 gr Varget averaged 2643 fps. These both fired at the same time on the day as the previously noted 175 SMK with 43.5 gr IMR 4064.
Also worth noting was the rifle, so far, has a tendency to jam when it gets warm and it only takes about 4 or 5 rounds to get warm. Sometimes it fails to fully eject the spent case causing the next live round to and spent case to get jammed together. A few times it had a sort of half stove-pipe jam. This was happening with factory steel magazines and the composite P-Mags. I plan to allow even longer cooling between rounds and see if this still happens. None of my rounds were fired with the cover closed. I left it open the entire time, so it had nothing at all to do with my failures.
It does shoot really nice so far, so I'll try to work out the bugs. It will hold a group under 1 moa better than I can, so next outing I'll trying to be more stable see what it can do.