Tim, I suspect that you might have a few things going on. First, Bradley really aren’t designed to run at 320. Many seem to top out at about 270 or so. Second, might be a combination of your ambient temperature and a breeze. Breezes across the exhaust vent really suck the heat out of the smoker. Protect the vent from the breeze. Third is management of your exhaust vent damper. For high moisture product, such as poultry, your vent damper should be 3/4 open. If the damper isn’t open enough, it traps moisture in your smoker, which prevents the smoker from getting as hot as it should. A last item that could cause the long heat up time you experienced is the water you used in your puck bowl. I fill my puck bowl with near boiling water because cold water in the puck bowl will absorb a lot of the heat put out by the heating element.
Hope something here might be helpful to you.
Tskeeter