Which sizing die?

[bigedp51]

Both Hornady and rcbs produced cartridges with high levels of runout. Simply switching my dies to Forster, cured the problem. For clarity, I changed nothing else but the dies. I took back a set of rcbs dies that were giving me .005" runout. That's junk. Hornady is usually .003 and Forster is .001 or less. Which one would you use?

I also prefer Forster full length dies and their high mounted floating expanders are what makes the difference.

If you remove the expander from any FL die and size the case it will be as straight and concentric as it ever will be. And with the expander in the die if it is locked down off center it will induce neck runout.

I replaced all my RCBS expanders with Forster expander and spindle assemblies to reduce neck runout.

Below a RCBS .223 expander raised as high as it will go on the left. And on the right a standard Forster expander assembly that is a direct fit on the RCBS dies.

Below a Redding FL die with a modified Forster expander assembly to reduce neck runout.

Below the Forster high mounted floating expander enters the case neck when it is held and centered in the neck of the die. Meaning the Forster expander can not pull your necks off center and induce neck runout.

Bottom line, if the dies expander is locked down off center you cases will have neck runout. And the Forster expander and spindle assemblies are self centering and do not pull your necks off center.

And a added benefit with Forster FL dies is Forster will hone the dies neck to your desired diameter for $12.00.

Added note, you can also remove the expander from any die and use a expander die to expand the necks. This expands the necks on the upstroke of the ram with the case sitting on its base. This reduces neck runout as much as the Forster die does "but" requires two sizing operations.