I was shooting some of the crushed rib Harvester sabots in .452 diameter using a 450 grain pure lead flat nose .452 projectile the other day. I was loading them in my Green Mountian Stainless Steel Barrel. As you said, I could push the projectile under the crown with just my thumb and then without the use of a short starter and just the range rod, could easily seat the projectile down on the powder charge. The accuracy was very good also....