When loading a .458 Winchester or Lott, I do not flare the case mouth. I use Lyman 50 caliber chamfer tools. A conventional inside and outside chamfer tool does the outside of the case, with much less fumbling than with conventionally sized chamfer tools on these big cases. I use the Lyman 50 caliber VLD chamfer tool to put a nice chamfer on the inside of the mouth. Four twists with the VLD tool will do it. A Lee factory crimp die, and seperate seaters for the softs and solids (and so marked)keep things very simple. I like that.

The neck tension is superior without flaring the mouth. I do not have any problems seating any type of bullet in these straight-walled cases. I am also meticulous about deburring the flash holes. I have found that this simple step makes a big difference in velocity variation across temperature extremes. Like in Canada, where I reside.