One of the shotgun choices that you have in cowboy action shooting is a Model 97 pump. Some of the fastest shooters find great success running these guns, but there is a unique skill set that you will need to develop in order for you to reach your potential with this model. One important tip is to not run this gun soft. In other words, when you drop the round in and run the pump forward, do it hard or this shotgun can lock up. Not a good thing to happen on the clock.
Another thing to practice is the way that you load the shotgun. The fastest way once you have these skills down is to load one shell at a time, but grab multiple shells off your belt at once. The following video will help you develop these techniques, and will give you some ideas for things to use in your next practice session.