Comments on: Try Using O-Rings with Sizing Dies for Reduced Neck Run-out

By: Vince

Vince — Thu, 04 Oct 2018 00:47:11 +0000

FOSTER CO AX floating system would seem to be the best solution. Certainly when using bushings they should be left a bit loose and when using O-rings chamber the first few pieces of brass and check every so often by chambering brass. For heavens sake put a mark on the die once you get it. On my full length Lee die the F for full length falls right on my die depth for the perfect shoulder bump using the feel method.RCBS micrometer,WilsonGage,Sinclair,Hornady all work ok to some degree. Feel method is great but best if firing pin removed from bolt or 3 way wing safety set in position so bolt drops freely with no pressure.JUST KEEP CHECKING BY CHAMBERING EVERY SO OFTEN.

By: Dasher

Dasher — Fri, 11 Jul 2014 18:11:51 +0000

The O-ring kind of makes it impossible to keep the should bump to what you want. It defeats the purpose of the other article

A little wiggle on the shellholder (not vertically) to let it seek it’s path is best. Also; do not tighten the bushing into the die, but keep it 1/8 of a turn clear so it too can find it’s own path.

Editor: You might be surprised. I’ve used dies with O-ring locking rings and been able to hold bump dimensions just fine. Good tip about letting the bushing float — that really can make a difference in run-out.

By: Chuck

Chuck — Fri, 11 Jul 2014 06:21:49 +0000

Since it’s been three years since this repeat has had a comment…….

I find it better to modify the slot the shellholder slides into allowing the shellholder to be held just a little loosely – this allows the case to center into the die as it enters rather than being held rigidly by the shellholder.
I use both Whidden and Redding size/seating dies and runout is nil and never stuck a case.

Cheers.

By: SP Clark

SP Clark — Wed, 04 May 2011 15:20:43 +0000

The o-ring functions as a centering aid by putting a slight load on the threads. Nothing more than the lockring does when it’s tightened against a press head. The value comes when the die “self-centers” a little bit on each case that’s being sized, and if you choose to make an index mark on each die (once you’ve set it to where it provides the proper headspace but make sure you don’t switch shell holders!) and your press it’s easy to return dies to the exact same position down the road.

By: 427Cobra

427Cobra — Tue, 03 May 2011 12:15:50 +0000

Or buy a Forster Co-Ax press!

By: JabaliHunter

JabaliHunter — Mon, 12 Apr 2010 21:43:05 +0000

There’s also a good write-up of this technique in Glen Zediker’s handloading book

By: German Salazar

German Salazar — Mon, 12 Apr 2010 18:51:21 +0000

As our editor Paul says, the index mark on the die and a quick check of the first few pieces of brass sized each time will confirm the headspace setting and it stays very consistent throughout the session. I’ve been doing this for about 15 years and it works beautifully. If you have a few rifles with slightly different headspace, it makes for very quick adjustment for each one. I have an article on setting headspace when reloading here: http://riflemansjournal.blogspot.com/2009/08/reloading-headspace.html if it’s of interest to anyone.

By: Dwight Larson

Dwight Larson — Mon, 12 Apr 2010 02:41:03 +0000

Whidden Gun Works has a clever fix for the Dillon progressive presses that accomplishes the same thing. The lock rings are notched to accept a roll pin (loose fit) that allows the die to self-align in the toolhead, but adjustments remain consistent because the die cannot rotate.

By: Editor

Editor — Sun, 11 Apr 2010 15:42:10 +0000

I have used the O-ring on my FL sizing die. Headspace control, at least on a short BR case, is fine. Using a Sharpie pen I put an index mark on the RockChucker press insert and on the locking ring. This way I can visually confirm nothing’s shifted. I then measure each case after sizing using a Harrell’s neck-shoulder collar. So long as I confirm the index mark hasn’t shifted, I can maintain my desired .0015 shoulder bump.

By: L. Dricken

L. Dricken — Sun, 11 Apr 2010 15:00:21 +0000

It’s all about line bore,keeping things
perpendicular,linear and “0” during manufacturing processes, reamers and taps
can walk during manufacturing.That includes the lock rings also.