Gentlemen,
I'm loading for a new G.A. Precision "Rock" Rifle in .308. Brass is fire formed from a Match 175SMK load and I'm using Forster Ultra Dies and a Forster Co-Ax Press. Runout is measured on a Sinclair Concentricity Fixture with a Starrett .001" Dial Indicator. The problem is that my FL sizing die, properly adjusted for headspace, is inducing neck runout in the brass from .002-.008" with the VAST majority being .007" and better. Bullet runout is obviously in the same range. Brass out of the chamber has no discernable runout. I've flipped the expander ball, per Sinclair, however, my runout is still too high. Case lube is Hornady One Shot with plenty in the necks... Your input would be greatly appreciated.

Regards, Matt.

Is it possible for the Forster dies to free-float in the press? Also, can you loosen the decapping-expander ball stem and let it free-float in the die? If so, try one or both of these expedients to help reduce run out to <.002". Hope this helps.

Have you looked at the case neck thickness? The brass maybe the problem instead of the die.
You might need to turn your necks to eliminate runout. Match brass "should" be quite even in thickness but you may have a bad batch.
The fire forming expands the case to fill the chamber which is consentric, but the die pulls to one side when the expander is drawn back through the neck and incounters thicker material on one side of the neck.

Try resizing without the decapper-expander ball in the die. Check your runout. Bet it is much better. If it is not start to suspect a bad die.
Even a slightly bent decapping rod can cause quite a bit of run out. Had that same problem with a .308 FL die.

I once had the same problem with a Forster full length sizing die in .222 Rem. All of a sudden accuracy when down, and when I measured my concentricity it was much worse than it had ever been.

I removed the decapping rod/expander assembly and all was well. It seemed that I had sized a case with a very undersized flash hole and in doing so I had bent the decapping rod slightly. The rod seemed to bend quite easily, but of course the rod in your .30 cal die would be larger in diameter...

jpb

Matt
I use a separate press for decapping all of my rifle cases. It's a small RCBS, a real light weight not of much use outside of decapping. I use a Lee universal decapping die.
When I resize I have the expander rod way up in the die, so as to not contact the bottom of the case. When I first set up the sizing die, the expander rod is loose, so that I can center it with the case as I pull the case out from sizing. Then I tighten to lock nut to hold it centered.
Something else I do is, when I push the case into the die I only go approximately half way sizing the neck then pull it back so I can rotate the case 90 to 100 degrees and then finish pushing the case into the sizing die.
I'm using Redding dies and a Co-ax press.
Jim

What Bob G said.

what I do to get maximum concentricity in resized cases is fully resize it, then I move the handle of the press up (the case moves down) until the die releases its grip on the case, I turn it half a turn and, resize it again in this new position.

the expander button is adjusted so that it goes trough the neck when the case neck is freed as case support from the die is much more at this stage.

hope it helps.

montero

I have the same set up for my stuff.
Throw the expander ball away, get a K&M Expander Iron, and all should be well. Those dies are the best, in my opinion...sakofan..
I got rid of the ball, but still use the decapping rod..

[ 07-21-2003, 11:47: Message edited by: sakofan ]

Gentlemen,
I greatly appreciate everyone's input. I'm slowly working through this problem and will reply when I've found the culprit... Thank you again.

Regards, Matt.

How far down is the decapping rod adjusted? I pull mine back until they just barely punch the primer out,..and even in the best dies,..this seems to reduce their run-out even further. If it is adjusted wayy down,..it seems in increase the run-out,..and in spades with some dies.

[ 07-22-2003, 16:55: Message edited by: JustC ]

Per the instructions from Forster, make sure the expander ball is sitting at about the same level as the vent hole in the die body.

Due to the design of the Forster de-capping/expander rods, failure to do so can result in significant problems.

RSY