wow.them sure look nice. what the price for his nk die and micro seater die
Here is his site Micro Dies
If you look at the picture I post on his bushing you see 334-20 the .334 is neck dia and the 20 is the shoulder angle. You can actually dial in how much you want to set the shoulders back or if you just touch them. The dies in the picture are his Mico Neck and seater for the arbor press and they have no case body insert not sure how he makes his FL sizer. If you look at his Threated Die
You see little description of the die which include this
THE DIE USES INTERCHANGEABLE HARDENED STEEL BUSHINGS, AND WITH THE PROPER SIZE BUSHINGS, IT WILL HANDLE VIRITUALLY ALL CARTRIDGES HAVING THE SAME HEAD DIAMETER.
That also includes the Mirco Neck die so my 223AI since I have bushing for the 222,222AI,223 and 222mag I can use that die for those cases. At today's price for the neck die I may have just under $300 so die cost spread out over 5 cases is less than $60.
Back in the 80's again when I started BR I was using the Wilson dies and wanting to do more with standard calibers one of my learning lessons was with Neil's threated neck die that used bushing. I'm sure it was easier for Redding to use the Wilson bushing than Neil bushing for their type S dies neck die.