Deformed brass

[GTIdentity]

Any ideas?

One of my ARs is a long range "sniper" rifle. It has a 20" barrel on a DPMS Low profile "slick" upper. No shell deflector.

http://i893.photobucket.com/albums/ac136/GTIdentity/IMG_0009.jpg

As my shells eject I believe they are whipping back around, 180°, and smacking the mouth of the brass on the upper. This can leaves a slight flattened deformation. As I am saving this brass for subsequent reloading I find this undesireable.
I am assuming that I could/should do something to lighten up the cycle pulse, if possible, to minimize this. I am considering changing the buffer and maybe the spring. I am not shooting hot hand loads. My beast's prefered load ia an HSM 75gr @ approx. 2800 fps.
I would appreciate any ideas from field.

Thank you!

[sdoperator]

Yeah, it's probably a little heavy. Softer spring, lighter buffer, lighter bolt carrier could be ways to improve it.
First to do is to check the gas system and make sure nothing's leaking. For instance, make sure port on the gas block is lined up with the barrel correctly, etc.

ETA: Forgot to mention, it could also be the exact opposite. :P Whatever you try, try the cheapest solutions first.