500, 590, or 590a1 Though the a1 may be a bit more.
Remmington has been having QC issues even on there police models. Not to say Mossberg hasn't but I haven't seen as much problems with them nor personal (well seeing a friend) run into issues. It's often something as simple as polishing the bore though.
Forego the PG. No joke. They are just silly, even if he wants a 'tactical' gun a pg doesn't do it. If he really wants a PG consider getting something like a speed feed tactical stock set.