Neck life and splitting from necking up

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Neck life and splitting from necking up

Post by Spooner » 17 Oct 2016, 10:21 am

Hi guys,

Just want to know for my own information, thinking of stuff in my head here, not trying to do anything.

When you neck cases up I guess you run the risk of splitting the necks?

Lets say going up from .30 or .338 or .375. Just an example but whatever, something significant.

And if they hold the neck must thin at least. Is case life reduced a lot?

As the case stretches up through firing does it re enforce the neck and save it a bit or once it's thin is that done for good.

Cheers. :thumbsup:
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Re: Neck life and splitting from necking up

Post by MalleeFarmer » 17 Oct 2016, 10:39 am

I too am interested in this as I'm considering a .338federal Build and have bundles of once fired .308 brass around. Otherwise I'd just go and buy 100rds of .338 Fed factory ammo and shoot it for brass.
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Re: Neck life and splitting from necking up

Post by MalleeFarmer » 17 Oct 2016, 10:51 am

Interestingly the circumference of a .308 bullet (read inside of neck) is .968 to the nearest thou.

A .338 has a circ of 1.062 that's .1" stretch from a .308

A .375 has a circ of 1.178 that is .2"
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Re: Neck life and splitting from necking up

Post by Lorgar » 01 Dec 2016, 11:11 am

You've pretty much got it.

A specific example for you would be anyone shooting .35 Whelan. Factory brass not so common on shelves at stores, so you neck up 30-06 brass.

Can't really offer you any data on life but thinning does happen, and potentially splits.

This is more of a stretch than necking up 30-06 brass to .35, but I have in the passed necked up .243 Win brass to .308 Win. Necks were obviously thinning in places just by looking, some where so thin they were getting seriously sharp and you could slice yourself with little pressure. That's a big leap though.
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