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Old May 13, 2011, 07:27 AM   #1
Doyle
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Is it easier to neck up or neck down?

Suppose I needed to load 7mm-08 and I had access to a bunch of .260 brass and a bunch of .308 brass. Which is easier to reform to 7mm-08 (and also give long case life assuming same brand of brass). I'm leaning towards the .308 because you aren't thinning out the thickness of the neck walls.
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Old May 13, 2011, 08:01 AM   #2
Brian Pfleuger
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It'd be easier for me to sell the 260 and 308 and buy 7-08 brass.
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Old May 13, 2011, 08:06 AM   #3
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I've never necked anything down, but I would imagine that you would have to turn the case necks to prevent too tight of a fit in the chamber.

I've necked plenty (100s of pieces) of .284 Win brass up to use as 7.5 swiss (7mm to .308) and never had a problem.

Use plenty of lube (Imperial sizing wax) inside and out.
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Old May 13, 2011, 08:43 AM   #4
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There is no particular difference in effort from necking up or down for your cartridge but it makes better cases to size down. Factory necks are so thin they make a sloppy fit in normal chambers so adding a bit of extra metal can be a good thing. Sizing down will make your new necks about 9% thicker, not likely to be enough to be concerned about but mike a fired case neck and compare it to a loaded round; if the new loaded stuff is smaller than the fired stuff you're in good shape.

Either way, you need to properly anneal the new necks or they will split quickly.

Of course it would be easier to buy new cases. But then, it's also easier to buy new ammo than to reload but few of us mind the trouble very much.
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Old May 13, 2011, 08:49 AM   #5
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I do not know how they do it when necking up and or down, as in getting thicker or thinner, if that happened brass would just wad up and plug the machine if that was possible, it could be others get their cases from the same place Jack got his beans, yes, magic cases.

My cases do not get thicker or thinner when necking up and or down, with a full length sizer die, the versatile die, my necks get longer when sized down, when the ram is lowered the expander ball is pulled through the neck, when the neck is expanded it gets shorter, never thicker or thinner, then there are those that never get around to understanding the simple sequence of events involved is sizing a case with the versatile/full length sizer die before they move on to bushing dies, X-Sizer dies and colet dies, then? They create a new set of problems like donuts? and wrinkles etc..

Measure before and after, neck the case down, the neck gets longer, neck the case up the neck gets shorter, unless.

I form cases, 308 W from 30/06, when forming 308 from 30/06 I do not move the shoulder back, or as some of the guys say "BUMP" I wreck-um, I erase the shoulder,, when I get through the case body became the shoulder and the shoulder became the neck leaving me to use a hack saw and file to remove close to .250 thousands brass protruding from the top of the trim/form die, If the cases formed in this manner are going to be used ion a 7.62 NATO type chamber the neck may not require turning/reaming but if the cases are going to be used in a 308 Winchester chamber anticipate reaming/turning the neck, and the best case to use for forming 308 from 30/06 is the Winchester, as they say the Winchester case is lighter and because it is lighter it is thinner.

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Old May 13, 2011, 08:51 AM   #6
Brian Pfleuger
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I suspect the OP is using 7-08 as an example, rather than reality. I could see doing it for brass that's not readily available.
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Old May 13, 2011, 09:37 AM   #7
F. Guffey
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I have no suspects about the question, he started out with "suppose", that would cause me to suspect the question was hypothetical, nothing changes, necking up and of down does not thicken and or thin the neck, for those that measure before and after, before sizing down, after sizing down and after necking up.

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Old May 13, 2011, 10:36 AM   #8
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Quote:
My cases do not get thicker or thinner when necking up and or down, with a full length sizer die, the versatile die, my necks get longer when sized down, when the ram is lowered the expander ball is pulled through the neck, when the neck is expanded it gets shorter, never thicker or thinner, then there are those that never get around to understanding the simple sequence of events involved is sizing a case with the versatile/full length sizer die before they move on to bushing dies, X-Sizer dies and colet dies, then? They create a new set of problems like donuts? and wrinkles etc..
I've never measured the thickness of the necks that I sized up, but I do see the necks getting shorter, as you mentioned....
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Old May 13, 2011, 11:05 AM   #9
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Quote:
I suspect the OP is using 7-08 as an example, rather than reality. I
Yes, I used 7mm-08 because it is halfway between two other common calibers.
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Old May 13, 2011, 11:08 AM   #10
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Quote:
necking up and of down does not thicken and or thin the neck, for those that measure before and after
I'm thinking that it has to. You have X amount of material (i.e. a fixed number of molecules of brass) to go around a Y circumferance. If you change the circumferance and don't change the number of molecules in your formula then the only way is for the thickness or length to change. Maybe it is the length that is getting changed.
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Old May 13, 2011, 02:33 PM   #11
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.308 to 358 easy with new brass

I once picked up a rifle in .358 Winchester. Not having any .358 brass I ran through a number of brand new .308 Winchester brass though the sizing die and necked them up to .358. I did use some graphite to ease the process but it did not take long and I then had 100 new shells to reload. I have also with the proper dies changed 30-30 Winchester to 30 and 357 Herrett. Very accurate rounds out of a 10 inch TC barrel.

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Old May 13, 2011, 03:10 PM   #12
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Neck thickness does, indeed, change.

I have formed many cases/cartridges. A short list of examples/results:
.22 Hornet to .270 REN = thin neck.
.30-06 to .35 Whelen = thin neck.
.280 Rem to .35 Whelen = even thinner neck (though, sadly, exactly the same as factory brass - due to the drawing process R-P uses).
.308 Win to .243 Win = thick neck.
.308 Win to .22-250 = even thicker neck.
.303 British to .22 Short Krag II = thick neck.
...and the list goes on.

When forming .35 Whelen from .30-06, the starting neck thickness is generally 0.018-0.019". Once expanded to .35 caliber, the neck thickness will generally be 0.015-0.016". That neck most definitely got thinner, unless you're suggesting my calipers magically change their zero for every post-forming measurement. I DO get a longer neck, as well; but that's because I iron out part of the shoulder, and turn it into part of the neck.

As for the original question-
Necking up results in thinner necks. If you're seeking sub-MoA accuracy at Creedmore, or need extreme neck tension, it's not for you. For most applications, it doesn't matter. -The farther you neck up, the thinner the neck will be.

Necking down results in thicker necks. You may encounter high neck tension (much more than desired), and difficulty chambering the cases/cartridges. How much this matters depends on the application, and the chamber in your rifle. Sometimes, you'll have to inside-ream or outside-turn the necks; sometimes, you won't. -The farther you neck down, the thicker the neck will be.


In the example provided here... if both types of available cases (.260 and .308) were of equal demand and value; I would neck up. Neck thickness will change only very slightly, from ~.260-.261" inside diameter to ~.280-.281" inside diameter. If you use digital calipers, accurate to only 0.001"... you may not even see a change.

However....
There is an additional complication to be aware of: The top of the shoulder of bottleneck rifle brass usually has a "donut" of brass around it. That donut gets relocated into the base of the neck of the newly formed (necked up) cartridge, and must be reamed out if it is detected at all. If you don't remove the donut, you can run into really funky bullet run-out, gas sealing, and sizing issues (especially with dies where a mandrel is used inside the neck sizing collet).


Best answer for a commonly available cartridge: Just buy the correct brass.
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Last edited by FrankenMauser; May 13, 2011 at 03:40 PM.
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Old May 13, 2011, 03:28 PM   #13
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"..necking up and of down does not thicken and or thin the neck, for those that measure before and after, before sizing down,.."

I do measure and that has not been my experience; the new neck thickness does change in my loading room. In fact, the thickness change is fairly predictable as a direct function of the percentage of diameter change. And simply necking a case down does not produce a 'donut".
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Old May 13, 2011, 04:35 PM   #14
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My experience is:Necking down,the case body is supported by the die,and so the concentricity of the neck is held.Necking up,the expander is not so rigid,the spindle can deflect.I have also found,necking up,the stretch does not occur uniformly around the circumference.One side will yield easier,resulting in non uniform neck thickness.
I always choose necking down at the press.If I must neck up,I do it by blowing it out using the Bullseye/Cream of Wheat process.That gives nice uniform necks.
Still,it seems obvious,if you can buy the correct brass,why mess with forming?
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Old May 13, 2011, 08:17 PM   #15
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Thanks guys. I'm still really new to the reloading thing so I'm still trying to wrap my head around some of the physics.
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Old May 16, 2011, 08:16 AM   #16
F. Guffey
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Doyle, "I'm still really new to the reloading..." that is a good start, try this with a new case and a full length sizer die adjusted to the shell holder in your press: Install a case into the shell holder, raise the ram (and then stop), remove the lock nut on the primer punch/sizer ball assembly then screw the assembly into the die as the ram is lowered, this will allow the case to be removed with the neck sized but not expanded, once the case can be removed from the shell holder remove the case with the expander/decaping assembly in the die (it will not come out), measure the case length then place the case and assembly back into the shell holder, raise the ram and guide the stem back into the full length sizer die (remembering to use a screw driver to secure the stem back through the die). After securing the stem then lower the ram, once the case is removed from the shell holder measure the case length again, it will be shorter, it is claimed the case gets longer when the neck expander ball is pulled through the neck, I find the case gets shorter, in my opinion the case gets shorter when the neck is expanded.

If you measure a case first, size first then measure and measure again after expanding the neck you will find the neck gets longer when sized down and shorter when sized up. Again I form cases, for me the most useful case is the 30/06 when necked up to 35 Whelen. Measure before and after, the case length of the 30/06 is 2.495 + or -, after necking up to 35 Whelen the case length is 2.460, that is .035 thousands difference, so, if you are being led to believe the case length does not lengthen or shorten when necking up or down you are being mislead.

What difference does it make, to most they do not have a clue, Me? I want to cover all the chamber I can with as much case as I can get, forming 30/06 to 35 whelen is not a good choice, forming 35 Whelen from 280 Remington allows me to cover the chamber with the case and use the extra length of the 280 Remington to off set the effect the chamber will have on the case when fired.

30 Gibbs, most 30 Gibbs were reamed from 30/06 chambers, not easy to clean up a 30/06 chamber with a 30 Gibbs reamer, as to the part where most do not have a clue, if the neck of the 30/06 chamber is the diameter of the 30 Gibbs is the same, no one notices, if the diameters re not the same the fire formed will notice 2 different diameters on the neck of the fired case, again, I want to cover all the chamber I can with as much case as I can get, gain the 280 Remington case is the better of the two choices. The 30 Gibbas a short neck, .217, that is shorter than the neck of the 300 Win Mag, again, Me? I want all the bullet hold I can get so I want the additional .035 thousands a longer case provides, then there is fire forming, I have been accused of doing some risky stuff, shortens a case when forming wildcarts,. there are claim by want to be wildcatters/fire formers that loose the neck of the case then ask "What"?

So the ideal the case length does not change when necking up and or down but only gets thicker or thinner makes for a very boring person to talk to when it comes to reloading.

http://www.z-hat.com/Cylinder.htm

30/06 type case that is 2.650 long, not understood by most but with a case that long there is no reason for a reloader not to know the effect the chamber will have on a case when fired, Me? I determine head space first, form then fire, others fire first then try to determine what effect the chamber had on the case when fired. Again, I have one Eddystone with .016 thousands head space, when I purchase cases at the range I want cases that have been fired in trashy old chambers and fired in particular rifles.

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Old May 16, 2011, 08:33 AM   #17
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I have made a series dies to neck down to a wildcat in 10% steps.
The brass must be annealed if is not already soft.
I hate doing it.

Necking up is worse.

But I do hear that 7mm-08 brass makes the best brass for sloppy per SAAMI 260Rem chambers.
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