I have a question about expanding case necks. What is the reason for the expanding button in a resizing die. When a case is resized, the die sqeezes the neck and body back to the shape it needs to be. Why if the neck is resized down is it necesssary to expand the inside out?

It's because neck thicknesses vary.

If you can resize without using the expander ball and have proper neck tension you usually end up with less runout......................DJ

Good question. One reason is brass thickness. If you have very thick brass and you size the neck from the outside then the inside may a bit small. The expander button brings the inside not the outside of the brass to the proper size.

Thanks for the info. So I'm better off not using the expander ball if I am getting proper neck tension without it. I am using Winchester brass.

quote:

Originally posted by wrsmith:
So I'm better off not using the expander ball if I am getting proper neck tension without it.

It really depends. I do not use an expander. I use Redding bushing sizing dies. Most of the time if you resize your brass, and it is quite a bit narrower than the expander, then you can actually create runout when you seat the bullet because the bullet is working the brass excessively while it is being seated. This tends to shave jacket material.

I use a graphite suspension to lube the inside of my necks before bullet seating. This pretty much eliminates jacket gawling.

Ideally, if you plan on not using the expander, you want to make sure that the neck is only sized enough to have good neck tension. Most dies squeeze the neck tighter than that. This is why I prefer a bushing die from Redding. You get to pick which bushing is best for sizing YOUR brass from YOUR rifle's chamber.

I am experimenting with a Redding bushing die and turning case necks. I just had a Shilen barrel installed on my rifle and I'm trying to get the most out of it.