I'll second what some other people have said- it really depends on the gun and the slugs. Certain guns like certain slugs- can make a huge difference in how accurate it shoots.

For example, with Remington Sluggers, my Win. 1200 shoots 12 - 14" groups at 50 yards. No, that's not a typo- there's no guarantee that you're hitting a pizza box at 50 yards with that combo.

Now with Federal Premium rifled slugs, the groups shrink to about 3" at 50 yards and 5" at 75 yards. Not going to win any contest, but certainly good enough for deer hunting out to 80 yards or so.