Sabot for gun launch projectile

From a plurality of sabots, a sabot is provided for shrouding a sub-caliber projectile to form a launch package in a gun bore for acceleration by an actuator behind the projectile. The sabot includes a forecastle, an aft bulkhead and a waist. The forecastle separates the projectile from the gun bore. The aft bulkhead abuts against the actuator. The waist connects the forecastle and the bulkhead by a radial spar that supports inner and outer flanges. The inner flange mechanically engages the projectile, and in preferred embodiments is concave. The gun bore is optimized as a pair of electromagnetic rails.