A shoulder thing that goes up?
? It's a 590A1. The heat shield is fixed around the barrel. I also have the bayonet lug, and bayonet (which will come in handy when lib zombies attack). The A1 also has the metal safety and trigger guard, unlike the non-A1. Collapsible stock. Don't know what is meant by shoulder thing that goes up, I'm a novice on that.