Neck sizing... where do you draw the line & go to full length ???

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Magnum Wheel Man

New member
semi autos... yep I get that, but how about magnum pressures ??? any other conditions???

I've started buying a few neck sizing dies for my smaller bottlenecked cartridges... just curious if this is something I'll start doing for every rifle that has a camming action closing, or if cartridges like 338 Win Mag ( for example ) need to be full length sized ???

Contenders ??? probably full length size, as the cartridges have to be manually pushed into the chambers... or are the pressures low enough, that I could try neck sizing there ???
 
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Unclenick

Staff
If you are willing to feed them one at a time by hand, then you're good to go. But any gun I thought I might need to be able to get a fast follow-up shot with would be fed cartridges whose cases had been full-length resized.
 
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cw308

New member
I wouldn't think a neck sized case would effect box fed bolt guns, only OAL would cause a problem with the round being to long.
 
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Unclenick

Staff
Magnum Wheel Man,

It's a matter of speed and ease of feed. I think rapid bolt work generally benefits from some of the same extra looseness in the case and chamber diameter fit that a self-loader does, though it may not be an issue with a case that has a pronounced taper, like a .30-30. I've not tried that particular round for speed feed.

Usually what happens with neck sizing is the case gradually becomes a tighter fit with each firing, and, depending how warm you load it, at some number of firings becomes tight, even for slow feeding, and has to be full-length resized again (at least enough to push the shoulder back a thousandth or two) and then started over on neck sizing. If you want reliable rapid feed, I would not be using fireformed brass unless I'd experimented with it carefully to prove it works well first. I would not trust it to continue to feed reliably at speed as it went through additional load cycles without additional testing.

For myself, for top accuracy loads I use a Lee Collet Die that I've modified a little (I should make a video of that process; all the world requires to be perfect is for time to stretch out a bit), followed by a Redding body die that bumps the shoulder back about a thousandth of an inch. This also narrows the case each time, but does not introduce needless case growth. Bart B. swears it produces even better accuracy than neck sizing alone will do, and awhile back I came around to thinking he's right. The case self-centers on the shoulder cone when you do this and if you are being careful to eliminate runout in your seating it results in a bullet that is essentially perfectly centered in the chamber neck when the pressure in the primer pocket pushes the primer back and sets and holds the shoulder firmly forward as the powder pressure builds. Such rounds also feed very nicely. It's as if every chamber were a match chamber.
 
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steve4102

New member
243winxb said:
For accuracy, its best if everything is the same at each firing. The neck sized 223 case has 4% more volume than a Fl sized case that has been returned to factory specifications. Different case volume, different pressure, different accuracy.
Click to expand...

That is debatable. FL sized with the shoulder bumped back a few "K" is not enough to increase pressures. Also, once the primer ignites and the process begins, the case has expanded to fit and seal the chamber before the bullet starts to move. This would mean that both the Neck sized case and the FL sized case would have the same capacity when pressures peak.
 
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dahermit

New member
I've started buying a few neck sizing dies for my smaller bottlenecked cartridges... just curious if this is something I'll start doing for every rifle that has a camming action closing, or if cartridges like 338 Win Mag ( for example ) need to be full length sized ???
Click to expand...
Magnum cartridges do not necessarily use higher pressures than standard cartidges....338 Win. SAMMI pressure = 64,000. .270 Win SAMMI pressure = 65,000. So, it is logical that if one can neck size a .270 in a bolt gun(many do), and get it to chamber, one can also neck size a .338 Win. and get it to chamber.
 
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chiefr

New member
Unclenick posted
If you are willing to feed them one at a time by hand, then you're good to go. But any gun I thought I might need to be able to get a fast follow-up shot with would be fed cartridges whose cases had been full-length resized.


I fully concur. Autos are more reliable with "Undersized" ammo. The military learned this years ago. The military prefers reliability first followed buy accuracy.

Any gun can chamber more reliably with with FL sized ammo, but then what is your objective. Accuracy or reliability?

On the otherhand for precision shooting in other than autos, you would want to NSO.

Also to be considered is case life. As we all know, NSO extends case life significantly.
 
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Magnum Wheel Man

New member
I guess I didn't mention intention in my 1st post... I was initially just talking about my "everyday" bolt actions ( I'm currently in a phase that I take one of my bolt action guns out, & shoot targets on my range, in distances from 50 - 300 yards ) so in this instance, accuracy is more important that rapid fire... however I could see neck sizing transitioning over to some or all of my hunting bolt action rifles... I already understood that full length sizing is needed in most semi autos to insure full chambering ( hence my comment on "camming action" in my 1st posts ) but I guess the rotary bolt semi's do have some camming action as well, so maybe I should have said bolt actions ???

anyway thanks for pointing out the pressures of some of the magnums aren't any higher than some of the other cartridges... I guess I'll have to look at the pressures individually & look at the case shape & design on an individual basis as well...

NICK... I'd be interesting in understanding better the accuracy advantage of bumping the shoulder back a couple .001's... so... are you saying, that if the barrel throat is not completely concentric with the chamber, there is no way to insure that the case is inserted correctly each time, & having the shoulder back a couple .001's... how does that help ???
 
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schmellba99

New member
Any gun can chamber more reliably with with FL sized ammo, but then what is your objective. Accuracy or reliability?
Click to expand...

There is loads of debate on whether neck sizing only produces better accuracy, or if FL sizing with a small (.002" to .003") shoulder setback is what produces better accuracy.

I used to neck size only - but every 4th or so load, I had to FL size because even when firing in the same gun, the brass will still grow to where chambering was tight. And the last thing you want is to have a round that won't chamber when you need it to, whether hunting or at the range or in competition.

I switched over to FL sizing with a .003" setback and have seen absolutely zero degradation in accuracy, but also no longer have the worry of whether or not this round will chamber correctly.

Magnum - bumping the shoulder back .002" to .003" allows the round sufficient clearance to chamber without sticking, but also doesn't give the brass too much room to grow upon firing. Too much room and the case will prematurely fail. Too little and you may not be chambered correctly, or it may not chamber at all.

With a .002" or .003" clearance on the shoulder, it allows the round juuuuuusst enough room to self center as the firing pin pushes the round against the chamber shoulder (headspace). If you have a decent chamber and good loading techniques (low run out, neck turned brass, trimmed case), this increases the likely hood that your round is either perfectly centered, or as close to it as reasonably expected, before the powder burns. If you are starting off square, it only increases the chances of everything working as best as the components and machine will allow. And if you can repeat this between rounds, you get a much more predictable result.

Now - for an off the shelf hunting rifle with a production chamber, you likely aren't going to notice much difference in performance. Especially at hunting ranges (say 400 yards and under). But at longer ranges or with match chambers, these little things can make a huge difference in performance of your ammo or rifle.
 
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F. Guffey

New member
“I've started buying a few neck sizing dies for my smaller bottlenecked cartridges... “

I have neck sizer dies, I have lots of neck sizer dies, I also have forming dies, I have more forming dies than neck sizer dies, my opinion the forming die offers more advantages to the reloader than the neck sizer die.

Favorite die: My favorite reloading die is the ‘VERSATILE’ full length sizer die. I can size cases for short chambers, that would be .017” shorter than a go-gage length chamber, I can also size case to infinity, that would be a case that is longer than a field reject length chamber by many thousandths, IF! it can be understood my versatile full length sizer dies is used to size the case from the shoulder of the case to the head of the case. I think it worth of mentioning I size the cases in length that vary in length by .001” because my dies have threads and my press has threads, and, I can verify the adjustment.

Then there is the feeler gage, the companion tool to the press, there is never a reason to make wild guestmates in fraction degrees of a turn or converted to thousandths, I eliminate the middle piddle, I go straight to the verifier, the feeler gage.

I have never got the ‘hang’ of bumping, I have bump presses, I have presses that not bump, the most difficult thing I find about reloading is how a shoulder can be bumped without the neck and case body being bumped at the same time, I know, there is a bump die as meaning? bump the shoulder. and that is impossible, the shoulder can not be bumped without upsetting the case body, unless of course, the case body is being supported, and, that brings us back to “How do they do that, bump the shoulder, without case body support? I do not know, I use the versatile full length sizer die.

F. Guffey
 
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Unclenick

Staff
I don't see how you can bump a shoulder without body support. That's often done by accident in chambering a round. You slam a round in real fast and if you extract the fired cartridge and measure the case, you find the shoulder has been set back a few thousandths, but the case body is now a thousandth or two wider as it has expanded into the chamber. That's what made room for the shoulder move without the force of a loading press or needing case lube to keep it from getting stuck.

The Redding body dies I use just are loose at the neck. Otherwise they are just the same as full length sizing dies. I set the should back a thousandth or two in one of these, then I trim and then size the neck separately with an inexpensive Lee Collet Die. I think setting the shoulder back by just a small amount is how the term "bumping the shoulder" was originally used, though I note that Forster has something called a Bump Die that I have not had an opportunity to try, so I don't know if it is doing anything truly differently. The guy who owns a Redding S FL die can use it as a body die just by leaving the neck bushing out of it. But that's an expensive die to use that way. May as well pull the expander and get the right size bushing and do both steps at once if you have one of those.


Magnum Wheel Man,

The main concern is that commercial chambers are often not exactly perfectly coaxial with the bore of the gun and bolt faces aren't always exactly perfectly square to the chamber. As a result, a case can come out slightly asymmetrical and then not fit back in the gun the same way until the case is rotated so the headstamp has the exact same orientation in the chamber that it did when it was fired the last time. In an extreme case, one fellow on the Shooter's Forum reported being unable to chamber some of his neck-sized-only cases at all. I suggested he try rotating the cartridges orientation in the chamber to see if he found a spot where it did fit, and he did that and it worked.

That's also a potential hazard for chambering from a magazine, and it also causes an accuracy issue in some chambers as the bullet is not cocked the same way in the chamber every time, even if you can squeeze the case in. Setting the neck back a couple thousandths and narrowing the case a little will both help the case fit and get the bullet in the neck the same way each time, whether the chamber's perfectly symmetrical and the bolt face perfectly square or not.
 
B

BuckRub

Moderator
I bought neck dies for everything I own. Reloaded both ways and feel you can get just a accurate with full length dies. Sold all my new neck dies.
 
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Unclenick

Staff
From the bushing dies you can if you remove the expanders and select the right bushings. The issue is about how sensitive your chamber is to bullet tilt. This video shows why.
 
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presence

New member
Does the full length die size the neck as well or do you still need to use a neck sizing die after the full length sizing die? My lee deluxe die set came with both and the directions arent very clear. It just lists them one after the other in order of operations. Doesnt specify either/or.
 
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BigD_in_FL

Moderator
ALL of my bolt guns are only necked sized and feeding issues are non existent. From 7mmBR to 7-08, 7mm mag, 6.5X55, 243 all were neck-sized and all had brass last for many reloads

Now, I do not have multiple guns in one cartridge designation - that would change things
 
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Old Stony

New member
In some of the old competition cartridges I used for silhouette, I always neck sized and never had a problem. With the contenders in cartridges like 7tcu, we would even index them in the chamber, with no problems.
I sometimes doubt there is a big difference in accuracy with either method of sizing. I remember once reading an old Sierra manual where they clamed better accuracy was possible by full length sizing as the case would sit in the bottom of the chamber exactly the same every time, instead of fitting snugly in the chamber.
To each his own, but I don't think there is a definitive answer to which is better and the debate will probably continue forever.
 
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BuckRub

Moderator
When I size my brass I full length size only. It takes a couple days to OCW and find the right bullet / powder and amount of powder but when it all works out you can make a jagged hole all day long. I don't think when you shoot a single hole a neck sizer won't help any at all. But the more items we buy the more money they make. I think alot of things are a marketing items. And we sometimes wanna believe we bought something that just brung us up to the next level. Lol
 
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