Mandrel die

JCSC · Feb 5, 2021

I bought a mandrel die for my 6.5 and it measure .2625. After sizing it leaves me at .261.

My Hornady FL die was netting me about .2615.

Is the purpose of the mandrel a matter of consistency? I was figuring I would end up with about .0025 neck tension.

Walkalong · Feb 5, 2021

JCSC said:
Is the purpose of the mandrel a matter of consistency?

Yes, when not neck turning, size the necks so the mandrel does slight expansion on all cases.

If you are using a full length bushing style die choose a bushing that will reduce necks just enough that the mandrel does just a little work on all cases so they are consistent in inner diameter.

If you are using a regular sizer with no expander, you will work the necks more than you need (Sizing down more than needed), but it will work.

JCSC · Feb 5, 2021

Thanks walkalong. I am using a FL die with the stem removed, So it sounds as if there is another piece to the puzzle in a bushing die.

I thought the benefit of the mandrel was more consistent neck tension and possible decreased ES. In hindsight I am not seeing how the expander ball is any different.

Walkalong · Feb 5, 2021

In theory yes, the expander ball does the same thing, but they can also pull the neck all out of whack, one reason is that the sizer has to over do sizing to make sure even the thinnest brass gets sized enough, then the expander ball opens it back up. A bushing style FL sizer gives us better control sizing the neck so we don't over size, but just enough so the mandrel does a little work, say .001 or so.

Mandrel die

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