I would definately go with some denser than lead shot out of a good choke in .665 to .670 constriction. The custom nitros are the best but very high. But you can do pretty well for a little cheaper. I shoot the Winchester Elite extended range number 6's out of a .665 Indian Creek choke. They are about 40 bucks a box. I am getting about 180 to 185 pellets in a 10 inch circle at 40 yards. My shotgun is a plain old 870 SM.