I've prepped the brass (primer pocket and flash hole uniforming, full-length resizing) and am ready to bell out the mouth of the case a bit for accepting the base of the bullet... 500 S&W that is, using a RCBS carbide 3-die set.
Here's my question ...how to adjust the expander die? The Sierra manual and the flier in the die set are nearly equally vague. I only want the mouth to be expanded enough to let the base of the bullet to go 1/32" into the case and stay there when gently turned upside down.
The expander die is a straight tube with the lock ring. The expander thing inside is a black gizmo that appears to be a 2-stage affair. Starting at the rounded end that points downward when installed, the expander has a particular diameter, then about 1/2" higher up, it expands to a larger diameter via a short 45-degree (or so) shoulder. I thought maybe this shoulder is what expands the mouth of the case, but the lower smaller diameter portion does not slip into the case (when tried by hand anyway, expander outside of the die.) The book just says "screw the die into the press until it just touches the ram, then insert a case and run it all the way up ...adjust the expander up or down to suit." Not much help there and why do they pretend the factory installation would be anywhere close?
So can someone explain how the expander thing is supposed to work (flared by the end or flared by that upper shoulder)? If it's flared by the upper shoulder as I think, then will the lower portion of the expander make the case too big or is it designed, not that the case is resized, to restore the inside of the case to factory-spec to fit bullets ...assuming that due to brass thickness differences, the full-length resizing will likely leave the inside diameter too small.
Here's what I think I should do: back out the expander enough to know it taint gonna bell that mouth properly, then keep running the case in and out while I slowly adjust it inward until I get the neck expansion that I want. I'm going to assume the lower, narrower, portion of the expander is SUPPOSED to be forced into the case in order to set the inside diameter right. No? Yes? BTW, I'm just working on my dummy round that'll be used for future bullet seater adjustments (make them quicker.) If I waste a case at this point, I'll get over it.