Hey sectshun8,
Rifled slugs are meant to be fired in smooth bores. With my 26" Improved Cylinder barrel they give decent accuracy out to about 45-50 yards. I know its ok to use rifled slugs in modern Cylinder, or Improved Cylinder barrels. I don't know whether it's safe to use them with any tighter-choked barrels than that or not. Maybe somebody else can comment on that.
If you have a shotgun with a rifled barrel, you can use "sabot" slugs which are supposed to be accurate (if fired from rifled barrels) out to about 100 yards. However, from what I've read, sabot slugs seem to perform no better than rifled slugs do in a smoothbore gun, and since they are much more expensive than rifled slugs, it wouldn't make sense to use them in a smooth bore. (Please note that I don't know this from any personal knowledge; just from what I've read elsewhere. I have no real hands-on experience with rifled barrels and sabot slugs.)
My experience is with one all-purpose shotgun, a 12 guage Remington Model 11 autoloader with an IC Barrel that was manufactured in 1937 or 1938. I have always used reasonably priced 2 3/4" Remington "Sluggers" in it, which can be found just about anywhere. I don't use a lot of them, but I use about a 5-pack of them a year and I've done that for many years, and have never had a problem with one, ever. Within their 45-50 yard accuracy range they're BIG hitters, and at least as effective on game as a 30-06 rifle bullet would be at the same range. I imagine standard Winchester slugs would be just as good.
I've heard that if you live in Alaska or somewhere else where you might realistically worry about running into a grizzly bear or Rhino or something, you might want to use Brenke slugs in a smoothbore since they are apparently harder than standard soft lead slugs and therefore may penetrate deeper. But regular Foster-type rifled slugs (for example, Remington Sluggers) give great penetration too, and they have a devastating impact, and are fine for any lower 48 big game, up to and including black bear, and personally, I wouldn't hesitate to shoot a grizzly bear with one, especially since I'd have 4 more left if the first one didn't do the job. So in my opinion, for hunting or home defense, Remington Sluggers work just fine.