I am by no means an expert on shotguns; or any type of gun for that matter. In Fact, Saturday I went Dove hunting, and for the first time in my life I attempted to shoot a moving target with a shotgun. I got 4 birds out of 40 rounds. Everyone else had automatics (man those things shoot nice!) This is what I was shooting:
That is a Savage model 77-D in 12ga.
At first, I was not getting anywhere close to the birds. But as the day went on I figured out my mistakes and I was able to stay on target; or at least close. One bird I fired at three times, taking the bird on my third, and last, shot. The recoil of a pump made it harder to keep on target, but it can be done. It is not easy to move that pump in a nice smooth linear motion. Especially when the gun kicks like an old grumpy mule.
I have never shot one, but I would imagine that the 870 is going to operate much smoother than my Savage.