I've been reloading some muzzleloader bullets like the Barnes-X, which perform really well at shotgun velocities. I've also tried some .45 and .50 cal. pistol bullets. There use to be a guy in PA. who sold a slug sabot combo that stayed together while in flight. The slug was called the Hammerhead. I got some pretty decent accuracy under 100 yds. I think his website was
www.shotgunslugs.com. I really want to develop something that will group decently out to 150-200 yds. I need to check my paper work and I will get a contact to you who sells sabots for .45 and .50 cal projectiles in a 12 ga. shot shell.