Runout

[ratbuster]

I have a Hornady New Dimension 20 VT FL sizer die to use prior to neck turning virgin Lapua 221 FB brass. Problem is I am getting neck runout. The runout averages around .003 but if I take the expander/decapper rod out of the die the runout drops to less than .001. I can look at the barrel of the die and see the decapper is not centered perfectly despite trying to center it.

I called Hornady who sent me another decapper assy but the results are the same as the first one.

After neck turning and first firing I will use a bushing die. I do not want to do that initially as I have been advised not to use a bushing die prior to neck turning as it will cause a weak spot at the neck/shoulder junction.

Would one expect the runout to minimize from the fireforming?

 

[/VH]

Yes sir, I would; as long as the chambering job was done well and the action is true.

 

[mikecr]

You should turn the necks as new with no more than expansion provided by your turning system expander mandrel.

Sizing the necks down, without expansion, is simply driving the thickness variance inward away from runout measure, potentially away from the turner cutter, and probably ruin proper turning mandrel fit.

 

[Brians356]

You should turn the necks as new with no more than expansion provided by your turning system expander mandrel.

Do you square up the neck ends first?

 

[FeMan]

If you are using a decapper/sizing button, I have had great results running the button up as high in the die as I could (so that it hits the button as soon as the neck clears the die) and leaving the nut loose so that it floats and self-centers. That does require separate decapping though.

 

[ratbuster]

You should turn the necks as new with no more than expansion provided by your turning system expander mandrel.

Sizing the necks down, without expansion, is simply driving the thickness variance inward away from runout measure, potentially away from the turner cutter, and probably ruin proper turning mandrel fit.

Mike,

Good suggestion....that is what I will do. After neck turning the new Fireball brass I'll use the Redding FL Vartarg bushing die. BTW, I fired my first 21 shots to break in the barrel. Indeed the brass is now concentric. I guess my chamber is pretty square and action fairly true...Yea!

 

[LCazador]

In all the years, and that goes back farther than I care to say, I've always used bushing dies without an expander button. That way you get a true fix on how much neck tension is in play. The expander button has always been nothing but a pain that introduces too many variables to the equation. By the way you should always full length size without the expander so that the shoulder is pushed back to the same point and the neck turning cut is into the shoulder the same amount. Of course after full length sizing, you will expand the neck with your neck turning expander for proper fit in your neck turner.

 

[Iowa Fox]

I got so fed up using expander balls 25 years ago I quit using them. I tried polishing them, waxing them, lubing the inside of case necks with a Q-tip with everything slippery I could think of. Nothing helped. All they do is stretch necks and pull them crooked. I don't even use them on my hunting rounds, got the best of the darn things by not using them anymore.

 

[ratbuster]

I have aquired 4 new dies recently and 3 of the 4 produce runout. Hornady VT FL non bushing and Redding FL non-bushing produce runout if used with expander buttons but no runout to speak of if used sans buttons.

The third offender is Redding S style FL bushing which produces runout with or without the expander. I am floating the bushing in this die.

The only die that does not cause runout is the lowest priced one...a Lee. It provides perfect concentricity with or without the button.

I am using adequate amount of Imperial wax and floating the shell holder in a Forster press.