What the heck is going on here?

[spike camp]

A friend told me he traded some labor for a AR platform 6.5 creedmoor.

I haven’t had a chance yet to check out the rifle, but my friend said the casings were showing some markings.
I didn’t know the severity until last night when I received these pics…

 

[Pilsner]

Following. A buddy's AR in 6 ARC is doing nearly the same thing. We have fiddled with the gas settings to no avail
Hoping this thread will generate ideas.

 

[HandgunHTR]

Looks like the rounds are sitting high either due to the feed lips being opened up, or the mag is sitting high and the bolt is running over the rounds as it closes.