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Removing expander ball on dies


MrDuston

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No expander on my Type S dies either but I use Lapua brass which has uniform neck walls and / or put an expander mandrel through the neck after contraction with the bushing.

If you have brass which is not uniform thickness all round and you don't neck turn then any off-centre tendency is transfered to the inside diameter by the bushing  which doesn't help concentricity any.

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I remove the expander ball on all my dies and just use the bushing size to control neck tension. No point in oversizing the neck to then drag an expander ball back up through it to get the to the size you require. To me that just adds potential inaccuracies and issues of neck concentricity. 

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I never use the expander ball that comes with a die. Always gets removed.

I do use the Sinclair Expander die and cal specific mandrel after F/L sizing my brass. That opens the necks just enough to give about .002” neck tension.

Think about what the die with expander ball does. The case goes in, expander ball opens neck then die shrinks neck. Extracting case from die then pulls the expander ball through again, opening neck.

So using an expander ball actually works the neck 3 times. If FL sizing without ball but using an expander mandrel, you size the neck, then open it a bit with the mandrel. Only works neck 2 times. Plus the mandrel pushes its way through, it doesn’t rip itself through the neck which has been proven to create issues.

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20 minutes ago, stephentri said:

If you don't neck turn you will end up with a case that's round on the outside but oval on the inside this will give inconsistent neck tension 

This is absolutely true. Sizing the neck (either FL or with bushing) forces brass inconsistentcies to the inside of the neck - the outside is nice and round. then the expander forces these inconsistencies to the outside again - the inside now being nice and round. By not turning the neck, the inconsistencies lie between the outside of the neck and the chamber (neck) walls.

I however don’t compete and neck turning simply isn’t something I can be bothered to do. Maybe one day.  

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Aaargh  ... now I want one 🤤

I feel the need to check my inner roundness. Hornady do a Wall Thickness Gauge that bolts into thier concentricity guage, U$60 (£47.50) at Cabelas and £74.45 (U$93) from CDSG .....

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