I have an 870 express supermag combo with the bird barrel and slug barrel. It has shot the 3" Remington copper solids fairly well. You could likely expected good accuracy, after trying several different brands of slugs to see which one your particular shottie liked. A rifle barrel is going to be more accurate farther out. I would say it is not unrealistic to expect 3-4" group @ 75-100 wards with the right set-up. Farther if using a scope.