I was advised that there will be a full pat down, inlcuding emptying pockets, at the gates next Sunday.
Leave plenty of time to get to your seats from your tailgating activities.
Also - new guidelines have banned backpacks from the stadium, even if they are clear (like mine). I was told that the NFL said that someone could hide a bomb in the straps of a backpack. Not sure how seat cushions are still allowed in, but anyways...
I had taken my camera & binoculars out of their cases so that wasn't an issue, but I can't guarantee they won't be prohibited too.
To avoid any hassles and/or delays, please use a clear plastic bag only to bring in anything to the stadium.
http://www.buffalobills.com/facility/StadiumPolicies.jsp