Over Resizing cases

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All handloading data posted on Full-Bore UK from 23/2/2021 must reference the published pressure tested data it was sourced from, posts without such verification will be removed.
Any existing data without such a reference should be treated as suspect and not used.

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Berger
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Over Resizing cases

#1 Post by Berger »

What should anyone expect to happen to the cases if they were over resized .cheers Berger
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WelshShooter
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Re: Over Resizing cases

#2 Post by WelshShooter »

What calibre do you have in mind? And what do you mean by oversizing?

If you're talking about full length resizing of bottleneck cartridges, you can't really oversize per se since full length dies are set up so that the bottom of your shell holder makes contact with the bottom of the die and you get some cam over. This should resize the case back to SAAMI specifications. You could potentially set the case shoulders back too far if you decided to mill back the top of the shell holder and/or the bottom of the die as this would push the case further into the die and push the shoulders back further than they should be. The result of this is that during firing the cases may stretch more than normal and result in a case-head separation. If you're using a bolt action rifle, you could measure the distance from the case head to a datum point on the shoulder and then adjust your die so that the shoulders move back around 0.002" to 0.003". I resized some .223 brass the other night and if I set the die up per instructions it would bump the shoulders back 0.010" from fireformed size, but after adjusting my die I now set them back 0.002". This still allows the case to feed into the chamber quite easily and minimises the work hardening of your brass.

If you're talking about flaring the neck cases like you would with a straight wall calibre, then you can dramatically reduce the life of your cases by causing splits in the neck after excessive flaring and resizing. You should only flare the necks enough so that you can start seating the bullet into the case by hand. Anything more is excessive. This operation should be done when loading any cast bullets as the sharp edges of the case can shave the lead (since the bullets tend to be flat based and not boat tail like the large majority of jacketed bullets).
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Re: Over Resizing cases

#3 Post by snayperskaya »

I think the OP may mean if you resize a case too many times.

If that is the case the brass will work harden and become brittle which can cause split necks etc.If the brass is full length resized too many times it can lead to case head seperation.
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Re: Over Resizing cases

#4 Post by Rockhopper »

Annealing can solve many of those issues.
Berger
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Re: Over Resizing cases

#5 Post by Berger »

I put a new ejector spring in my bolt and so i though I would custom fit the brass with the chamber as I had bolt apart.the new ejector spring gave the bolt closing extra tension/resistance that I wasn't aware of as the rifle is new to me.its a 7mm saum.my other rifle are set up this way which I found easy to do.it wasn't until I was seeing how much a 284
Lee case trimmer pilot would need modifying I noticed the pilot wouldn't fully insert in the case which caused my concerns and tried to figure out what was wrong/had gone wrong.now I've worked out what went wrong I need a fix.over sizing had pushed brass from the shoulder forward into the base of the neck just below where bushing die doesn't resize. I will expand them all.neckturn the brass and resize again.do i need to ream the inside of the necks aswell.cheers Berger
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Re: Over Resizing cases

#6 Post by phaedra1106 »

I assume this is your post on TSD then?, Laurie has given a excellent reply (as usual).

https://www.thestalkingdirectory.co.uk/ ... ver-Resize
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Re: Over Resizing cases

#7 Post by Maggot »

If you over full length re-size (and by this I mean your die not set up to reset the case to spec) you risk getting case head reparations as the case thrusts back against the bolt and shoulders to take up the slack headspace.

This happened to me when I set a die up as per the norm and did not check the rounds were the correct headspace. I was getting case seps in 3 firings or so.

A Dillon gauge with the bolt action setting for the AR showed me I was pushing them back too far and the rifle has run fine ever since.

Annealing will NOT stop this happening as this is applied to the neck and shoulders of the case, although it might slow it down, the annealed but will just be worked harder.

In some cases it pays to neck size only. You should always look to work the brass as little as possible to achieve reliable feed and good results
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Re: Over Resizing cases

#8 Post by Berger »

Cheers maggot.thanks for replying.I am aware of all these things.i have done this process several times noiw custom fitting the brass bump to the chamber.the new ejector spring tension/resistance caused me to do it..cheers Berger
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Re: Over Resizing cases

#9 Post by Berger »

[quote="phaedra1106"]I assume this is your post on TSD then?, Laurie has given a excellent reply (as usual).

https://www.the
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Re: Over Resizing cases

#10 Post by Berger »

Headspace gauge arrived today and I've checked headspace and I only oversized by 5 thousandths so not as bad as I thought shakeshout
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