My old RCBS 9mm dies have a full length carbide insert. It sizes the tapered case just like a regular steel die. Paid a fortune for it back in the late 80's. Same concept as 30 carbine carbide dies. Presumably to save money some manufacturers use a short ring that doesn't fully size the case. Evidently it works. Others like Redding are using two rings. Perhaps that helps. I think the best solution is a full length carbide insert, if still available and if one is willing to pay the price.