ewc,

Post-mortems on sabots are somewhat inconclusive. I've heard people say that the smaller diameter bullets tend to spread the sabot petals out further and also carry them further downrange before seperation - all of which would be very bad for accuracy. Your loss of the petals might be an indication of excessive projectile speed which damages the petals, causing them to fall off once they clear the barrel. If so, the larger bullets would remedy this as they would slow down the muzzle velocity somewhat - depending on powder charge.