Bushing dies and brass flow??

[bodywerks]

As brass is fired, doesn't the brass tend to flow forward? Wouldn't this cause the neck of the brass to slowly get thicker? If true, wouldn't this make external bushing neck sizer dies less consistent than traditional dies?
I know I'm wrong, but I want to know why I just spent $250 on a set of redding Type S match bushing dies(because they come highly recommended) for my 338LM instead of $35 on an RCBS expander-decapper type die, lol!

 

[MitchAlsup]

Re: Bushing dies and brass flow??

As brass is fired, doesn't the brass tend to flow forward? Not so much when fired, but brass does have to flow forward whenthe case is sized.

Wouldn't this cause the neck of the brass to slowly get thicker? Yes, as the sholder flows into the neck area the neck gets the "dreaded doughnut".

If true, wouldn't this make external bushing neck sizer dies less consistent than traditional dies? The big killer of concentricity is the expander ball. As the expander ball upsizes the neck, it also pulls on the sholder and can pull the sized neck off center. Bushing dies do not have this kind of problem.