Did you thoroughly remove the burrs from the ejector channel extrusion before getting those measurements?
I measured 2 cases, there was a clean flat spot between the burrs but I'll clean one up and measure again. I got an email that the rifle arrived yesterday so there's time to fiddle with brass.
The thing about the brass chewing is it's not consistent. The spent case front and center in the previous picture was fired along with the other four on the same gas setting with the same suppressor all just seconds apart from each other. Same type of burring intermittently happened with the lighter PPU cases both suppressed and unsuppressed ... I need to go back and check those for loose primers. Two of the primers in those Rem cases just fell out but two others were loose in the pocket.
Besides the inconsistency in burring and primer popping I just don't personally know anyone else with a 308AR that chews up brass like this or pops primers. My other 308AR dented case necks pretty good before I replaced the gas block with an adjustable. Now it's fine but it weighs nearly 3 lbs more than this one thus the desire to switch.
Someone might say "well, uh, dems dare ammo is jus too *hot* fo dat rifl" but that is near tantamount to saying this rifle is potentially not safe for factory loaded 308 Win. which is almost like saying it's only safe for punching paper with MilSurp ammo.
Did Ruger just release the "308 Govt." (e.g. 45-70 Govt.)? They need to put a caution label on it for what ammo to avoid.
When it comes back I'll take it out again "as-is" from CS and if it's not up to my expectations I'll replace the gas block with something "infiinitely" adjustable and schlep it to the range with with an assortment of buffers and springs in hopes of taming it down.
ETA: If I can improve things considerably with a block, a buffer and maybe a spring then I'll start looking for a way to improve dwell time but everything behind the shoulder is around 0.628" so I'm not exactly sure about how to approach that one. I don't think my old Liberty Freedom will index off the muzzle, maybe I'll hit Dave up to see if he has any ideas.
If I can't get it to work right I'll put a label on it that says "MilSurp ammo only" and sell it for $600 in the H-E-B parking lot.