Advanced precision loading technique with standard dies.

[Fred M]

When loading factory brass with standard FL dies you are usually over
working the the necks making them hard and brittle. Resulting in shorter case life and various neck tensions, which is not at all accuracy enhancing.

Consider the following 257 Roberts Handi or any other 25 cal. By taking measurements any other cartridge can be used.

Fired neck diameter  0.292
Sized neck diameter 0.2805"
Neck wall ave.          0.0165"
Inside diameter after sizing is 0.2805 minus 2x 0.0165 or 0.033" = 0.2475"
Expander button on die is 0.2555".

Here is what happens. You first size the case neck down from .292 to 0.2805
or 0.0115".

Next you expand the neck from 0.2475 inside to 0.2555" or 0.008".
The outside is now 0.2555 or a bit more because of spring back plus neck wall 0.033 =0.288".

It is not unusual to stretch the case when pulling the expander button out,
expanding 0.008 or more destroying tuned head space.

Here is what I do to get less brass working and good concenric necks.
I outside neckturn the necks to 0.013 this allows for 0.0002 stress relax.

So this is what you end up with.  0.2805" less 2x 0.013 or 0.026" = 0.2545"
The expander ball is now redundant. For more or less neck tension adjust the
neck wall thickness. 0.0025" neck tension has worked well for me on all
hunting ammo with moly plated bullets.. 0.00012" on target and BR ammo.

You need the following tools using a FL die or a neck sizing die without the expander ball and decapping pin. This works nearly as well as a bushing die.
Loaded ammo is 0.283" resulting in 0.0045 radial clearance which is more
than you need but not too bad if the neck is concentric. A tighter chamber
neck would be better, like 0.281" on my 25 Hunter with 0.001" radial
clearance and a 0.011 neck wall.

A universal decapping die
Outside neck turner ( K&M is what I use)
Tubing mic to measure 1/10000"
1" Mic to 1/1000
Case trimmer (All cases must be trimmed to 0.0005" tolerance, lest you cut into
the shoulder.)
6" caliber 1/5000

[aulrich]

I had been wondering about neck tension and my 204, I have observed one batch of loads was significantly more accurate that my other batches the only difference was that they were made with brass that had been used with trial loads that were rejected and had the bullets pulled and I reused the cases for those extra accurate reloads.

What should I be doing to properly investigate this.

[Ireload2]

Did your extra work have any affect on accuracy?

I have a Redding Type S .308 neck bushing die. Due to the short fat nature of the .308 case desiign it will hold a bushing while permitting you to size many different cases. Here is a list that I put together.

List of cartridges that could be neck sized with the .308 bushing die with the proper bushing

.22 Savage High Power
.219 Zipper
.22-250 Rem.
.220 Swift
.243 Win
6mm Rem
.25-35 Win.
.25 Remington
.250 Savage
.257 Roberts
.25-06 Rem.
.260 Remington
6.5 Jap
6.5X52 Carcano
6.5X53R Dutch
6.5X54 MS
6.5X55 Swedish Mauser
6.5-06
.270 Win
7mm Waters
7X57 Mauser
.280 Remington
7X64
.30-30 Win
.30 Remington
.30-40 Krag
.308 Win  and its clones.
.303 British
.303 Savage
7.65X53 Mauser
.32 Win Special
.32-40 Win
8X57 Mauser

Does not work with .358 Win or .35 Rem
Might work with .338 Federal or .338-06

There are many wild cats that it would neck size also.

[Fred M]

Quote.
What should I be doing to properly investigate this

You can bet on inconsistent neck tension and various neck wall thickness.
These small cases are very fuzzy about these two items. My 6x47 Handi cases are
all neck turned and loaded in a custom honed bushing die which does full length sizing, set the shoulder back to 0.001" head space. The body is sized to provide 0.0075" radial clearance. Accuracy is constant at about 0.350" with this Handi

Ireload2.
Recently I reloaded 7x57 RWS cases with  7mm-08 dies. The first loads with the
new brass I just seated the bullets with no sizing at all. These first loads
using 140 gr Nosler BT produced 3/4" groups.

The second time a rezized them in the FL 7mm-08 die. same seating depth.
These loads shot 1.5 to 2". I quit after two groups and checked the loads
with my concentricity and wall runout gauge. These loads had as much as 0.007" neck and bullet run out. The reason for this is of course the case body of the 7x57 is not supported by the 7mm-08 die and the shell holder adds a bit of play at the bottom..

When you neck size a case that is not supported by the die or the die is not concentric you are most likely producing cockeyed ammo. This was my first time to use a die that was not the proper size for the cartrige.

Now I have a proper RCBS 7x57 die and the ammo is concentric with minimal
neck turning. BTW the RWS cases are perhaps the most dimensional
consistent brass cases. I have 40 more ordered from Germany. I bought 50 Rem
7x57 cases, they were so dimensional bad I toke them back to the store.

I can not agree using cases that are not supported by the die body. There are no short cuts to accuracy. Now if you are happy with 1.5"-2" dispersion then the above is not applicable. In this case one size does not fit all.

[Mac11700]

There is an old saying...use the right tool for the job...Sure...I can make a chisel out of a flat tip screw driver...but...

Mac

[Ireload2]

When the bushing is sized so that you do not reduce the necks so far under size you have to use an expander your accuracy improves without all the neck turning. BTW benchresters have been using neck bushing dies that do not support the case body  for decades.
The main problem folks have with neck dies is they size the neck way too much and then pull an expander back though it.
Here is a small sample of sizing die neck measurements. As you can see most size the case way too much.
For me the .308 bushing die is handy. I can neck size many rounds that I do not have dies for. Many of the rounds that I shoot will only group into 1.5 to 2 inches because the rifles have no scope, that includes some I shoot cast bullets in.

Cartridge     Brand      TYPE       DIAMETER
         
.357 Auto Mag   RCBS   TRIM      .385
8X57               RCBS    TRIM   .350
8X57               RCBS    TRIM   .350
.308                RCBS    TRIM   .340
7.65 Mauser    RCBS     TRIM        .339
.308               RCBS      TRIM   .338
.300 SAV    RCBS      TRIM        .337
7.65 Mauser   CH      TRIM        .336
.308              BAIR             FL     .328
.308               RCBS     NECK       .327
7x57              CH        TRIM   .322
7X57             RCBS       TRIM       .315
7X57              RCBS        FL            .306
7MM/08        HORNADY   FL      .305
7X57          FORSTER      FL         .304
7X57           HERTER       FL          .299
6.5x53R           RCBS     TRIM        .295
6.5   JAP   PACIFIC      TRIM        .291
.250 SAV   RCBS     TRIM       .286
6.5X55             RCBS        FL           .286
6.5 CARCANO    RCBS   FL       .285
6.5X55                RCBS    FL          .285
6.5X250 SAV.     RCBS     FL       .284
6.5X55                 LEE   FL   .284
6.5 JAP                 LEE   FL   .283

[Fred M]

Quote.
BTW benchresters have been using neck bushing dies that do not support the case body  for decades.

For a casual onlooker this may look that way, I shoot BR and have 3 sets of
BR dies for 6PPC, 30BR and 25 Hunter. Let me assure you when the case is
bottomed out they are supported all the way. They are not too tight since
they are used with a arbor press and eject with little pressure. They use no shell holders.

The dies are custom made by Wilson from fired cases and measured and made
to nearly zero tolerance. Any BR shooter worth his salt won't have dies where the case falls into a sloppy die let alone using one of a different caliber.

Bushing dies are made to use with neckturned cases and without the
expander ball.The way you use them is ok since you are not concerned with top accuracy. I am concerned with precision ammo and accuracy.

The Redding S-die with the bushing is a poor design since it lets the bushing float to accomodate excentric necks. I have one S-Die that made some real
crooket ammo until I wrapped the bushing with a thin steel shim stock
to center it in the die body and won't move no more. If you can't produce concentricity you can't produce accurate ammo. It is just that simple.

[Ireload2]

Fred,
The only time I have had any trouble with eccentric ammo was due to a bad seating die that was returned to the factory.  The die had about .030 run out in the seating stem.  That was 1976.
When you push a case into a bushing die the case is not supported when the neck sizing starts. What you seem to be saying is that the bushing die should be capable of straightening the neck just as it bottoms out. Prior to bottoming out there is no support due to the case taper.
I have a Neil Jones neck bushing die for the 6X47. The die is bored straight through and the bushing floats. The ammo is used in 2 Remington 40X BRs set up to be switch barrel. The original factory barrel has a chamber that permits use of factory brass without neck turning. These rifles shoot groups with unturned unprepped brass in the threes.
If you start with reasonably decent brass, neck turning has little affect on the accuracy when the chamber has clearance around the neck. This is especially so with military chamber like the 7X57 that has a lot of clearance round the neck. When you turn your brass for the 7X57 you simply wind up with more clearance. When fired the brass has to stretch more before it is constrained by the chamber. The less the neck is sized the better but the bullet still has to be seated straight. Extreme care to control head space can also yield accuracy improvements due to the consistent centering of the case shoulder even when the neck has a lot of clearance.
One of the problems you may have had with the type S die is excessive sizing using the Redding bushings. The Redding bushings do not have much of a radius or chamfer on the edge of the bore. Polish a large radius on the inside edge and use a bushing diameter that gives minimal sizing and I think the eccentric necks will improve. If you  size the case neck .007 when pushing it past a relatively sharp bushing edge you will force it off center as it begins forming.
Norma factory loaded ammo 7X57 measures .311 over the neck. The same brass fired measures .326 over the neck. If you look at my data you will see the various 7mm FL dies range from .306 to .299. Sizing a case neck from .326 down to .299 or even .306 is likely to result in off centered necks. I would much prefer a .309 bushing to turning the neck to creat even more clearance.
 

[Mac11700]

Since we are talking Handi rifles here..let me say 1 thing...The best non-Arbor die's you can use off the shelf is these...http://www.forsterproducts.com/Pages/ultraseat_dies.htm...both the bullet AND the case is held in alignment..and will yield results that will rival any other type die for general usage...including good arbor set ups...They can be honed to your specifications at the factory and can ordered from the factory or most on-line dealers for less than the top of the line Redding bushing dies..

As to using odd ball dies for sizing various cartridges...I don't and won't recommend it..I firmly believe in using the correct tool for the job on hand..I've held this belief all thru my 45 + years of reloading...

Mac