I've tried Foster slugs in my rifled barrel, and was not impressed. They were OK, but not as good as Sabot slugs. I like the Hornady sabots for my 20 ga. 870. It would be nice if the Fosters shot as well since the sabots are definately in the rip-off category. I ran across a cache of old BRI slugs at a reasonable price, and am looking for more.