I have not seen the show or heard them referred to as AP 8 but has to be the same group. They are kind of like grower vigilantes. Growers themselves and they police other growers, they don't want people to step out of line and draw the attention of law enforcement.
If I remember the story correctly it went something like this: Someone in the Alder Point area had killed somebody, I think for trying to rip off their grow. The cops wanted to solve the case and it was getting a lot of attention. The AP boys show up at the guys house in a van wearing hoods and carrying assault rifles, grab the guy and beat the shit out of him until he agrees to surrender to police and admit what he did which is what he did.
It's been a few years so I am fuzzy on the details but I think I got it pretty close.