Partial case sizing


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39 shares, 31 points

 

A strong press like this Lee Classic Cast single-stage is a good choice for full length sizing any case up to .50 BMG,
A strong press like this Lee Classic Cast single-stage is a good choice for full length sizing any case up to .50 BMG,


Question

I have a die set which has a full-length die but no neck sizing die. The “expert” at my local
gunshop told me that I don’t need a neck-sizing die and to partially size cases in my
full- length die. What do you think of this method?
– Lennie Hewitt

Answer
I don’t think much of the advice you’ve been given. Attempting to partially size (neck-size)
certain cases in a standard full- length die by backing the die out so that the case is not
pressed all the way in sometimes results in ammo that won’t enter the chamber at all.

This is especially true of tapered rimless cases with gentle shoulders like the .257 Roberts
and 7mm Mauser, and is caused by brass being displaced as the case body begins to be
squeezed down which has to go somewhere.

In some cases the displacement actually results in the case shoulder being moved forward.
In full-length sizing the die resets the shoulder properly at the very end of the stroke,
but when partial sizing is attempted, the shoulder is not pushed back into place and the
case is left too long in the head-to-shoulder dimension to allow the bolt to close behind it.

But even if this doesn’t happen, cases which are partially sized in standard dies may
gradually swell throughout several firings and eventually become hard to chamber anyway.

If you are really set on neck-sizing only, I suggest you buy the correct die. Actually,
I’ve adopted the habit of resizing almost everything full-length and only have neck- sizing
dies for the very few rifles in which I wish to partially resize my brass.

I have no more case failures than if I neck-sized only, and, more importantly,
I am sure of proper mechanical functioning, feeding and extraction with my rifles
in the hunting field. Nothing is more important than reliability in your hunting handloads.

 


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Nick Harvey

Nick Harvey is one of the world's most experienced and knowledgeable gun writers, a true legend of the business. He has been writing about firearms and hunting for more than 65 years, has published many books and uncounted articles, and has travelled the world to hunt and shoot. His reloading manuals are highly sought after, and his knowledge of the subject is unmatched. He has been Sporting Shooter's Gun Editor for longer than anyone can remember. Nick lives in rural NSW, Australia.

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