There's a reason why they never really took off - accuracy suffers greatly, at least to unacceptable levels. I bought 25 sabots years ago and shot them with 55 gr 223 bullets out of a 300 Win Mag. Loaded from "Powder puff" to Max Loads and was able to keep most within a 12" circle at 100 yds, but no better. I did not chrony them, as I was concerned with debris (i.e. The sabot) striking the chrony, however I estimate that the MV's ranged from about 2500 to 4500 fps.
Interesting and fun to try, but not practical IMO.