Is the ar10 a slick side or does it have a brass deflector. If there is a deflector on it check it for brass marks. I’ve seen 223 that hits it hard enough to bend the mouth like that. Brass should iron out when you run it through the sizing die either way.
The case to the left looks as if it has two flat spots. The one to the right has a different type of deformation and what appears to be some marks on the shoulder from contact with a hard rough object such as concrete. My take is that the cases were deformed after they left the receiver and that changing the buffer would not cure the situation.
If you have a spare ejector spring you might take a shot at cutting a coil at a time to soften the throw of the case. With a spare you can always go back if you go to far on the clipping, not that I have ever made that mistake.