[Unclenick]

The steel sizer includes the taper in the auto cartridge case, where a carbide sizer is just a ring that sizes the whole case to the same diameter. That can flow brass to the rear where the taper of the steel pushes inward more with less rearward massage. My .45 Auto cases, shooting light target loads, actually lose about half a thousandth of length per sizing cycle in a carbide sizer. I've never run the experiment with steel, though, which might be interesting to try.

Also, Redding now has a carbide sizer design with two carbide rings. The ring near the case mouth is the same size as current carbide sizer rings, but the lower ring is wider to maintain the taper. I don't know how that will compare on final length, but it should work the brass less, improving case life for those firing loads at near maximum.