Thread: Filthy cases shooting suppressed (piston AR)

I've noticed that when I shoot suppressed I get quite alot of carbon blasting back into the action, enough so that the rounds in the magazine get cruddy too. If this is what a piston AR is like then I can't imagine what a DI gun is like? I have my gas regulator set to the lowest setting too but it doesn't make much difference.

Without having done any research into the issue, And this being my first AR... My only guess is I need a heavier buffer? Like an H3 or an H3 silent? I'm guessing the back pressure from the suppressor is causing the bolt to open slightly before the piston hits it And some of the gasses still burning escape around the shell?