The 1-66 twist being so slow will have a hard time with most conicals. The barrel is best known for its ability to shoot round ball. There is nothing wrong with round ball. They have taken deer for many years and will for many more to come. I would stay away from the sabots. You would not stablilize them fast enough and I think your accuracy would suffer. Not that you could not shoot them, because you can. You can try them and see what happens. If you want to shoot conicals, I would try the conicals made by
http://www.prbullet.com/ Precision Rifle Company. They are the makers of Dead Center sabots. They also make conicals specifically designed for the 1-66 twist and 1-60 twist. If their conicals in that twist shoot anything like their conicals made for the 1-48 twist, you will not be disappointed. They are also well known for their sabots in the faster 1-28 twist rifles.