Neck Cracks

[bubba300]

I am getting some neck cracks in a few cases(30-06 necked down to 6.5) ,first noticed it on some nosler brass that has quite a few reloads threw them and they were annealed 2 firings back,started using my lapua brass and noticed a crack in the neck of one of them and they have about 5 or 6 firings threw them.
I am working up a load for hunting this year with 130 gr accubonds and my rifle has around 1400 rounds threw it now so I am lengthing out bullets now to 3.400 from 3.340.
I have shot some 139 gr lapuas and Vlds with no problems at the 3.440 .
Just wondering if it is a length problem with the accubonds.

 

[curseyou]

Are you sure you got the annealing right? How many firings did the brass get since new? How many annealings?

I don't see how the cartridge OAL "lengthening the bullets" as you say by seating them further out could cause neck cracks, but that is just me.

 

[Slamfire]

Varying the overall length will affect pressure. But what's that got to do with neck cracks? Work hardening from re-sizing reduces ductility which result in cracks (brittle failure).

 

[Shooter ----/]

Over working brass during resizing and improper annealing.

 

[bubba300]

The Nosler brass could have 8- 10 on them,this is the 3 firing since annealing and it could be brittle but I have shot 65 of the same batch of Lapua with the vlds and scenars with no problems(I shoot the 100 brass and size them all at once) just thought it might be bullet seated out to far doing it. nosler book says max is 3.440 for the accubond.
I will keep an eye on them and maybe anneal them before next sizing.
How many rounds are most guys shooting the lapua brass before annealing.

 

[Ron AKA]

Here is something you should do to figure out what is happening:

Within one brass type - say Lapua:

1. Measure your brass neck OD of a fired round before resizing - That is the maximum your neck is forced to be, and is determined by your chamber neck size.
2. Measure your brass after resizing, but with the expander ball out of the die - That is the minimum your neck is forced to be.
3. Measure your brass after you loaded it - That is where it sits stressed until your fire it

The difference between #1 and #2 is the extreme working cycle of the brass. The larger it is the more you work harden your brass, and the fewer cycles it will take to crack it. There are two ways to reduce the cracking potential:

1. Anneal more often. I anneal my Lapua brass after 5 firings. When you anneal do it in the dark and heat until the case glows dull red in the dark. That is a proper anneal. It only takes a few seconds at that temperature (about 750F).
2. Cycle your brass less. This is best done with a bushing die with no expander ball, or an expander ball that just kisses the ID of the case on exit. With a bushing die you can minimize how much the neck is sized down. Most FL dies grossly oversize the neck down. The issue will be whether or not you can get a busing die in 6.5x06. You MAY get away with a Forster Bushing Bump die for an 06 with a bushing for a 6.5 mm. Worth investigating...

And the other issue could be that the neck size in your chamber is too big making the #1 measurement high. The solution to that is ugly -- new barrel with a tighter neck!

 

[bigedp51]

The greatest stress the case neck is exposed to is when fired and stretching to meet the chamber walls.

The second is during resizing and the case neck being reduced in diameter.

The third is how much the expander then increases the neck diameter.

Are Your Sizing Dies Overworking Your Rifle Brass?
http://www.massreloading.com/dies_overworking_brass.html

We live in a plus and minus manufacturing world, and no two chambers and reloading dies are the same diameter.

NOTE: At the Whidden custom die website they tell you they get the "least" amount of neck runout with standard non-bushing dies.
This is because when then the case neck is reduced more than .005 with a bushing die you will induce neck runout.
Bushing dies work best with tight neck chambers with neck turned brass.

Bushing Dies and Honed Full-Length Sizing Dies
http://bulletin.accurateshooter.com/2012/11/bushing-dies-and-honed-full-length-sizing-dies/

 

[bigbull]

Here is something you should do to figure out what is happening:

Within one brass type - say Lapua:

1. Measure your brass neck OD of a fired round before resizing - That is the maximum your neck is forced to be, and is determined by your chamber neck size.
2. Measure your brass after resizing, but with the expander ball out of the die - That is the minimum your neck is forced to be.
3. Measure your brass after you loaded it - That is where it sits stressed until your fire it

The difference between #1 and #2 is the extreme working cycle of the brass. The larger it is the more you work harden your brass, and the fewer cycles it will take to crack it. There are two ways to reduce the cracking potential:

1. Anneal more often. I anneal my Lapua brass after 5 firings. When you anneal do it in the dark and heat until the case glows dull red in the dark. That is a proper anneal. It only takes a few seconds at that temperature (about 750F).
2. Cycle your brass less. This is best done with a bushing die with no expander ball, or an expander ball that just kisses the ID of the case on exit. With a bushing die you can minimize how much the neck is sized down. Most FL dies grossly oversize the neck down. The issue will be whether or not you can get a busing die in 6.5x06. You MAY get away with a Forster Bushing Bump die for an 06 with a bushing for a 6.5 mm. Worth investigating...

And the other issue could be that the neck size in your chamber is too big making the #1 measurement high. The solution to that is ugly -- new barrel with a tighter neck!

Bingo, x2

If I may add, if the working range of your brass is high do not be afraid to anneal after evey firing or two.
BB

 

[Ron AKA]

NOTE: At the Whidden custom die website they tell you they get the "least" amount of neck runout with standard non-bushing dies.
This is because when then the case neck is reduced more than .005 with a bushing die you will induce neck runout.
Bushing dies work best with tight neck chambers with neck turned brass.

That does not make sense, and can only happen when you are using the wrong bushing size. You select a bushing that only sizes down to give you a 0.002" fit. It is the same as a custom honed neck die. The difference is that with a custom honed die, you are kind of hooped when you change your brass. With a bushing die, you just have to change the bushing.

 

[bubba300]

Ok found another problem today,looks like I bumped shoulders to much on my Lapua brass and had 3 crack at .30 from the base,measured brass with the precision mic and I have about 20 that I have bumped the shoulder to much,not sure how just 20 out of 100 are got like that but oh well its done .
I am gonna anneal them and size and hopefully that will solve my neck cracks.Got some cases to practice annealing on now.
Thanks for the response"s.

 

[Ron AKA]

Ok found another problem today,looks like I bumped shoulders to much on my Lapua brass and had 3 crack at .30 from the base,measured brass with the precision mic and I have about 20 that I have bumped the shoulder to much,not sure how just 20 out of 100 are got like that but oh well its done .
I am gonna anneal them and size and hopefully that will solve my neck cracks.Got some cases to practice annealing on now.
Thanks for the response"s.

Hornady make a cartridge "headspace" gauge that you can use to check to see how much you have bumped the shoulders. Normal practice is to only bump 0.001".

 

[bigedp51]

That does not make sense, and can only happen when you are using the wrong bushing size. You select a bushing that only sizes down to give you a 0.002" fit. It is the same as a custom honed neck die. The difference is that with a custom honed die, you are kind of hooped when you change your brass. With a bushing die, you just have to change the bushing.

The bushing floats inside the bushing die and you can hear it when you shake the die when it is setup correctly. This means the bushing can move from side to side, up and down and even tilt. This is why it is recommended when reducing the neck diameter .005 or more you size the neck down in two steps.

Bushing dies work best with neck turned brass with even neck thickness. If unturned brass is used the thin section of the case neck is compressed more causing warped case necks. This is why bushing dies come with expanders to make sure the inside of the neck is more uniform after sizing.

Bottom line, the average reloader with a SAAMI chamber will make more concentric ammunition with standard non-bushing dies. I get the most neck runout with bushing neck sizing dies and the least runout with Forster non-bushing full length dies.

And there is a reason why Whidden custom dies sells expander ball sets with five expanders in .001 increments, and tells you standard dies produce more concentric ammo.

"The non-bushing sizer die typically yields more concentric ammo in our experience. It also fully sizes the case neck fully to the shoulder for smoother functioning.
Neck tension can only be determined by changing expander balls with the non-bushing die."

http://www.whiddengunworks.com/wp-content/uploads/2015/02/Bushing.NonBushingExplanation.pdf

 

[bigedp51]

Ok found another problem today,looks like I bumped shoulders to much on my Lapua brass and had 3 crack at .30 from the base,measured brass with the precision mic and I have about 20 that I have bumped the shoulder to much,not sure how just 20 out of 100 are got like that but oh well its done .
I am gonna anneal them and size and hopefully that will solve my neck cracks.Got some cases to practice annealing on now.
Thanks for the response"s.

Normally bumping the shoulder back too far will cause and lead to case head separations.

Are your case neck cracks around the circumference of the case neck or are they longitudinal cracks?

Many bushing dies do not size all the way down the case neck to the shoulder junction.

Your cracks may be at the limit of the sizing operation of the bushing and at the greatest stress point of the brass.

 

[Purple shoulder]

I agree that annealing is in order but I don't think you shoud get them glowing at all, even in the dark.
This video is pretty informative about proper annealing. You dont need an expensive machine to do it properly but it helps with consistency.

https://youtu.be/fiIrLvAUh6o

 

[Ron AKA]

http://www.whiddengunworks.com/wp-content/uploads/2015/02/Bushing.NonBushingExplanation.pdf

I see nothing in that article to support your claim that bushing dies size the neck more than fixed neck size dies. In a bushing die you put the bushing in that does the very minimum possible resizing. The starting point for sizing is determined by the neck size in your chamber. As far as not resizing right to the shoulder, I do that intentionally. I only resize 2/3rds of the neck. That leaves the remaining 1/3 to fit with about 0.001" clearance in the chamber. It makes sure your bullet is concentric with the chamber. While most do not use an expander in a bushing die, I prefer to use one that just kisses the ID as I believe at the end of the day, ID consistency is more important than OD consistency. The knock on expander balls is that they can induce concentricity issues. However, that is usually caused when the ball is located too far down in the sizing die. In a Forster the expander ball is located as close as possible to the neck, so the neck is still in the bushing when the ball starts to enter the neck. Have a look at the drawings in this link for a better explanation.

 

[Ron AKA]

I agree that annealing is in order but I don't think you shoud get them glowing at all, even in the dark.

If you don't get the neck/shoulder up to a very slight dull red in the dark, you are wasting your time. You have to get the temperature up to 750F for a few seconds, which is where brass just starts to show a glow IN THE DARK. Have a look at this article. It covers a lot of ground, but start by skipping down to the procedure described in the last couple of paragraphs.

You can't anneal near the base of course. That cracking has to be solved by reducing the sizing die bump to 0.001 to 0.002", and no more...

 

[bigedp51]

I see nothing in that article to support your claim that bushing dies size the neck more than fixed neck size dies.

I said nothing about bushing dies sizing the case neck "MORE", I said the bushing floats inside the die and when reducing the neck diameter .005 or more you can induce neck runout.

There is a reason why competitive shooter prefer tight neck chambers, and in a standard SAAMI chamber the case neck can expand over .005.

There is also a reason why Whidden custom dies tells you non-bushing dies produce resized cases that are more concentric. (less neck runout)

Meaning the average shooter with a SAAMI chamber can end up with "MORE" neck runout when using bushing dies.

I personally see no reason to use bushing dies with off the shelf factory rifles with their larger diameter chambers.

I also do "NOT" think using a resizing die with a expander is the end of the world, and Forster will hone the necks of their dies to your desired diameter for a modest fee.

The OP needs to measure his fired case necks to see how much they are expanding in diameter when fired. And then check how far the necks are being reduced in diameter when sized.

Meaning he needs to find the reason his new cases are having cracked necks when resized after so few firings.

 

[Ron AKA]

I said nothing about bushing dies sizing the case neck "MORE", I said the bushing floats inside the die and when reducing the neck diameter .005 or more you can induce neck runout.

I personally see no reason to use bushing dies with off the shelf factory rifles with their larger diameter chambers.

I apologize. I miss read your post. I read it as saying bushing dies size 0.005 more than non bushing. Why use a neck bushing bump die with a factory rifle? Here is why. Three consecutive 3 shot groups from bushing die reloads.

And the other reason is that bushing dies work the brass in the neck the least amount, reducing risk of cracking, and extend the time between needing annealing.

 

[bigedp51]

Ron AKA

I have seven different type and make .223 dies and my Forster bushing bump die produces more neck runout than any of the other dies.

This is because the body of the die does not fully support the case body and the die reduces the neck diameter more than .005.

My Forster non bushing full length bench rest dies produce the least amount of neck runout.

I am getting some neck cracks in a few cases(30-06 necked down to 6.5) ,first noticed it on some nosler brass that has quite a few reloads threw them and they were annealed 2 firings back,started using my lapua brass and noticed a crack in the neck of one of them and they have about 5 or 6 firings threw them.
I am working up a load for hunting this year with 130 gr accubonds and my rifle has around 1400 rounds threw it now so I am lengthing out bullets now to 3.400 from 3.340.
I have shot some 139 gr lapuas and Vlds with no problems at the 3.440 .
Just wondering if it is a length problem with the accubonds.

The OP is sizing down 30-06 cases to 6.5 which makes his necks "THICKER" and if he is not neck turning the increased neck thickness is causing him to over work the case necks.

The OP has also not told us what type dies he using, his neck thickness or if he has gauges to even measure his case necks.

The OP has not told us if the cracks are running the circumference of the case neck or longitudinally, and if his die is using a expander on his "THICKER" case necks.

Right now we need more information from the OP and stop arguing about the type of dies we like to use. More information would make our "guesses" more accurate.

Ron AKA, this isn't a pissing contest about preferred sizing dies, its about finding out why the OP is getting split necks.

 

[Dogleg]

That does not make sense, and can only happen when you are using the wrong bushing size. You select a bushing that only sizes down to give you a 0.002" fit. It is the same as a custom honed neck die. The difference is that with a custom honed die, you are kind of hooped when you change your brass. With a bushing die, you just have to change the bushing.

Picking a bushing for .002" tension doesn't compensate for a huge neck area in the chamber. I think what Ed is getting at is that a solid die gives more guidance when the case needs a lot of sizing from fired to your .002 under. A floating bushing will size it down, but not neccessarily in the center. A neck die or neck bushing die is just along for the ride, the case will do whatever it wants.


Ooops, I see Ed answered for himself. Carry, nothing to see here folks.