The present invention relates generally to a one-piece sabot for holding a sub-caliber projectile. For use in muzzle loading and other firearms, the sabot includes a plurality of petals which, in one embodiment, encapsulate the projectile. The petals have a high mass portion near the barrel end of the sabot. The portions are subjected to a centrifugal opening force as the sabot exits the firearm barrel upon firing. The centrifugal force causes the petals to clear the flight path of the projectile quickly so that the sabot is less likely to interfere with accurate projectile flight. In one embodiment, the sabot may further include a protective surface for engagement with a ram rod and for protection of the encapsulated projectile, for increased aerodynamic stability.