My oldest set of carbide dies are RCBS in 9mm, no taper at all at the insert. They work fine, even on my 550, I just can't go quite as fast. I would give any of the current manuf a try. Redding is top notch, but I have had good results with all of them, even Lee. BTW, you only need 0.002" clear on the carbide insert to keep from cracking it. I set up the 9mm with a sheet of paper as the shim to the shell holder.

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NRA Cert. Inst. IDPA CSO