You would have realized it when you went to drive the bullet/sabot down. Without a bullet the sabot would go much easier. We won't ask about how I know that to be fact now will we. I would say either your first solution was the correct one or you may have gotten a bad primer. Also, from what I have observed when my sister is shooting that Blackhorn stuff, it really likes a good heavy seating pressure. It acts up if you don't lean on the rod pretty heavy.