Back about 25 or so years ago, I acquired about fifty rounds of Smith and Wesson saboted slugs which they made under license from BRI (I believe). Anyway, the slugs were hard-cast, intended for law enforcement and to penetrate car bodies. I have decided to start using up old ammunition. Took the S&W sabots to the range with my Ithaca Deerslayer II. The problem with the original sabots was that they often stuck to the slug and did not release uniformly and so they produced an inordinate amount of flyers, Well, these babies were all over the place. I had two distinct groups about 8 inches apart at the 25 yard line. A control group with modern sabots proved the Ithaca shooting right where I left it last time I sighted in. i really think Foster slugs would have been more accurate.
My advice is, if you still have any first generation saboted slugs, blow them off in target practice. Don't chance using them while hunting.