Full Length or Neck Only; What's Best Resizing for Accuracy?

Orange Dust

Well-Known Member
Joined
Oct 23, 2015
Messages
1,553
I suggest you do some reading of the aforementioned manuals.
We used to do this years ago with RCBS dies. What you are actually sizing depends solely on the amount to body taper. You are sizing part of the neck, and may or may not be sizing part of the body depending on the cartridge. This method actually works fairly well with cartridges with ample taper and a long neck. .222, 6MM Rem, 220 Swift, and .308 and 30-06 come to mind. Will not work with any of the AI cartridges, Weatherby's, and many of the newer magnums due to the lack of taper pushing the shoulder forward, keeping the round from chambering easily. In the old days we were taught to use a nickle to set up the die. Put a nickle between the die and shell holder and tighten. It was always called partial resizing. Nothing including the neck is fully sized with this method.
 

BountyHunter

Well-Known Member
Joined
Jun 13, 2007
Messages
5,243
Location
Wilmington NC
When did that happen?

I don't think Sierra's HPMK bullets ever went from coin, cup, draw, trim, heel, core and finally point machine went direct into green boxes. Nor did any retail lot have bullets from more than one such machine. I've toured both of Sierra's plants several times and there's 3 more stages they went through before going into green boxes.

Only their 1000 count brown box HPMK's sold at rifle matches bypassed those last three stages. They still had sizing lanolin on them but shot more accurate than those in green retail boxes. I've bought several 30 caliber HPMK ones in 168, 180, 190 and 200 grain weights; about 40% below retailed 100 count green boxed.bullets.

View attachment 171101

These were "standards" that tested in the zeros and ones used as quality control tests in their rail gun test barrel's accuracy. I've chatted with Sierra's Martin Hull, Rich Maholz and Kevin Thomas about all this. Sierra stopped this direct sales program when they moved to Missouri. I was able to get two such boxes of 30 caliber 155s in 1991 as I helped develop 308 Win load data for their first production lot of that new Palma bullet before they were sold at retail.
In the late 90s and 2000s that was the practice after they moved in 1990. They had a lot of problems with ogive variance when we really started measuring them in late 90s. As I said, I found a variance of.018 and sent a box or two back to prove it. I retoured Sedalia plant 2-3 years ago and Rich made a point showing the new process, one machine and one operator and the positive effects it was showing. Every machine had a slightly different set of dies just due to wear etc.
 

BountyHunter

Well-Known Member
Joined
Jun 13, 2007
Messages
5,243
Location
Wilmington NC
setup you FL DIE NORMALLY for FL SIZING AND Back it of 3/16” generally. If you read Hornady Handbook of Cartridge Reloading 3rd addition it will debunk some of what others have said about neck sizing...
That is for taking the brass back to factory SAAMI specs so they will fit in any chamber, not max accuracy or case life.

Here is the hornady video for max accuracy and case life. Listen carefully and you will hear them say exactly that.. "Set the die to touch the shellholder and then back off one complete turn."
 

Bart B

Well-Known Member
Joined
Dec 25, 2005
Messages
2,667
setup you FL DIE NORMALLY for FL SIZING AND Back it of 3/16” generally. If you read Hornady Handbook of Cartridge Reloading 3rd addition it will debunk some of what others have said about neck sizing...
Case bodys are then typically sized down enough to move their shoulder forward increasing their distance from the case head a thousandth or more. That often requires extra force to close the bolt; a known cause of reduced accuracy.
 

Orange Dust

Well-Known Member
Joined
Oct 23, 2015
Messages
1,553
Case bodys are then typically sized down enough to move their shoulder forward increasing their distance from the case head a thousandth or more. That often requires extra force to close the bolt; a known cause of reduced accuracy.
Yep, if you want to neck size, use a neck die. FL size with the die set to push the shoulder back .001-.002
 

Buck Buster

Well-Known Member
Joined
Jan 3, 2017
Messages
620
Let’s go at this logically: 1)You buy factory ammo. 2)You fire it through your weapon fire forming the brass to the chamber of your rifle and creating brass that is CUSTOM FIT TO YOUR WEAPON. 3)The only problem is the neck opening won’t hold the bullet properly. Why would anyone change brass that was custom made for their weapon and bother to reload in the first place?!
Seating the bullet into the rifling finished the alignment, The theory was as I understood it in the 70's and was to be true to perfect alignment as possible, with the machining of the chamber and rifling, and it assured each round was as near to being exactly the same. All I know is it worked well back then and it works well today for me, I don't shoot a lot like some, no competition shooting, just hunting and steel, or rock busting. I have never had a casing go bad, that's how little I shoot the bench gun, but I have had the cases I full length resize go bad, necks start to split is the main problem. I would think that FL sizing would be harder on a case then just neck sizing, you are working the brass more.
 

Bart B

Well-Known Member
Joined
Dec 25, 2005
Messages
2,667
How does one do it "right"?
Full length size the fired case (in a gelded die without an expander ball) setting its shoulder back a thousandth or two, reducing body diameters a thousandth or two and reducing the neck diameter so its inside diameter is a thousandth smaller than bullet diameter. Now the neck axis is aligned with the shoulder and body axis.

Seated bullets don't need to touch the rifling lands in the throat. They'll be well aligned with the bore axis when the round fires then travel bullet jump distance to engage the rifling. Case shoulder is hard pressed into and well centered in the chamber shoulder when the round fires.

Sierra Bullets championed this process in the late 1950's and competitive shooters soon moved away from neck only resizing. Their largest test groups got much smaller. Their smallest test groups stayed about the same size.
 
Last edited:

Orange Dust

Well-Known Member
Joined
Oct 23, 2015
Messages
1,553
Full length size the fired case (in a gelded die without an expander ball) setting its shoulder back a thousandth or two, reducing body diameters a thousandth or two and reducing the neck diameter so its inside diameter is a thousandth smaller than bullet diameter. Now the neck axis is aligned with the shoulder and body axis.

Seated bullets don't need to touch the rifling lands in the throat. They'll be well aligned with the bore axis when the round fires then travel bullet jump distance to engage the rifling. Case shoulder is hard pressed into and well centered in the chamber shoulder when the round fires.

Sierra Bullets championed this process in the late 1950's and competitive shooters soon moved away from neck only resizing. Their largest test groups got much smaller. Their smallest test groups stayed about the same size.
And this is why you also have to have concentric necks. The bullet cannot be true to the shoulder without turning the necks.
 

Bart B

Well-Known Member
Joined
Dec 25, 2005
Messages
2,667
Let’s go at this logically: 1)You buy factory ammo. 2)You fire it through your weapon fire forming the brass to the chamber of your rifle and creating brass that is CUSTOM FIT TO YOUR WEAPON. 3)The only problem is the neck opening won’t hold the bullet properly. Why would anyone change brass that was custom made for their weapon and bother to reload in the first place?!
To make the case neck axis better centered on the case shoulder and body axis.

It's a popular opinion that rimless bottleneck cartridges lay in the chamber bottom when fired.

In second place may be the popular belief that case heads are held against the bolt face while the round fires.

Both are myths.
 
Last edited:

Tikkamike

Well-Known Member
Joined
Dec 26, 2009
Messages
4,951
Location
Big Horn Basin, Wyoming
In my opinion Yes.
But there is more to centering the bullet than just neck sizing. cases need to be prepped and turned before they are ever fired. Then with minimum sizing or Neck sizing the chamber will hold the cartridge in perfect alignment. The concentricity of the loaded ammo also has a bearing on centering the bullet.

So keep In mind that one or the other method may not be any better if all the other conditions are not dealt with.

J E CUSTOM
Interesting, can you explain why the necks should be turned before they ever fired? Seems like if you sized fired cases with a mandrel type die that the imperfections would be transferred to the outside of the neck where the high spots could then be trimmed off?
 

Orange Dust

Well-Known Member
Joined
Oct 23, 2015
Messages
1,553
I'm going to say this and shut up about it. If you want the most consistent ammo possible for long range hunting, buy both a Sinclair and a Hornady gauge. They are both great tools and measure differently. Make every one of your cases as nearly the same as possible. Then use the gauges to find weaknesses in your reloading process. You want every round as straight and concentric as possible. Once you go down this path you can try different dies, and setups to see what works best in your equipment. You can create consistent and repeatable results. Don't be afraid to experiment, just measure the results of both the ammo and groups. I will also say if you want to shoot 400yds or less none of this matters and is a waste of time unless you are shooting very small targets. 500 is iffy. As range increases, and you go to bigger guns with larger expansion ratios, it is essential.
 

Latest Classifieds

Top