Excessive Case Neck Runout - How To Improve?

[Phil3]

A relatively new reloader, but need some input from experienced reloaders.

I just full length sized 50 new Winchester cases (223 Remington), with a Redding FL die (non bushing type) and floating carbide button in place. Press is a Forster Co-Ax. Results are not good. As it came out of the bag, the cases did not look that bad averaging around .0015" neck wall thickness variation and .0035" neck runout. After the resizing, virtually all cases had neck runout of at least .004", with some at a whopping.008". Is this just the way it is with full length sizing dies, or is there something amiss with my procedure? Or, are bushing dies the only way to improve runout? I have read that use of bushing dies for ARs may not work well, since the bushing does not size all the way down to the shoulder. Not sure why this would not be an issue with a bolt gun too... I would like to see runout around the .001" area, assuming the neck thickness does not vary and contribute to the runout. How best to achieve this?

- Phil

[J-cat]

That's what you get for using standard dies. They oversize the neck and then drag an expander ball though. This stresses the brass. The more you stress the brass, the more runout you'll get.

I once did an experiment where I sized the case neck down in .001" increments using a Redding competition neck die. The case maintained .001" runout until I sized the neck more then .003". After that, it was a crap shoot. Some maintained low runout while others went crazy. There was no rhyme or reason to it.

I repeated the experiment with Lee's Collet Neck Die. Despite sizing the neck as much as .008", it maintains runout under .002". It is a wonderful die and cheap too.

[killshot44]

Filthy, I bought the Hornday Lock N Load Concentricity tool last month to check/correct my runout.........

Turns out I don't have any. Everything measured at or under .002". I measured 75 loaded rounds before I quit....

I use Redding Bushing dies.

[Lead Waster]

http://bulletin.accurateshooter.com/2010/04/try-using-o-rings-with-sizing-dies-for-reduced-neck-run-out/

Here's a tip. You might be the perfect candidate to tell us if it works! (It involves putting an O-ring under your lock ring to provide a little bit of "free-float" for the die)

[Phil3]

Good idea, but I use a Forster Co-Ax press. The dies do not thread in at all. The dies use a locking ring that can be secured around the die (either by clamping the die or a set screw such as Redding uses). The die/lock ring assembly snaps into a slot on the press (real fast to change dies). The die can move in a horizontal plane and also can rock slightly, permitting it to self align. This in addition to floating shell holder jaws means the case can find its own center pretty easily.

- Phil