Help diagnose...Case Neck Separation???

M

Marc

New member
A fellow shooter asked me at the range what might be going on with his brass and showed me these. What are your opinions on what is happening to this brass. appears to be some sort of case neck stretch separation as you can see it is on the inside and outside of the necks you can feel it like a reverse donut on the inside of the neck. How common is this and what might cause it. About 1/3 of his cases show this to varying degrees, some with one ring some with 2 distinct rings.

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The case neck separations that I've witnessed were the result of improperly turning the necks prior to fireforming.

al
 
Sorry, I should have mentioned that the necks have never been turned, it's a .223, factory chamber, Winchester brass. He was not sure exactly but figured the brass had been fired at least 15 times. Took a look with the borescope and the chamber neck shows no machining marks that would correspond to whats on the brass.
 
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I would guess...

That this is a case of over worked brass in a factory chamber resulting in work hardened brass that is causing the separation. If no other steps are taken in his reloading techniques (subbing custom dies and bushings to reduce brass expansion), I would recommend he replace his brass after ten re-loadings.

virg
 
The circular lines on these cases are far to uniform to be separations,from
streching which is the cause of nearly all separations. If they are not caused
by the chamber, I would think the die should be closely inspected. Neck
separationsn are quite rare when not related to neck turning.One exception to that is a semi auto.
 
Bob Kingsbury said:
The circular lines on these cases are far to uniform to be separations,from
streching which is the cause of nearly all separations. If they are not caused
by the chamber, I would think the die should be closely inspected. Neck
separationsn are quite rare when not related to neck turning.One exception to that is a semi auto.
Click to expand...

And to expand on what Bob's saying.... the difference in distance between the two lines has me totally confuzzled.

Is it possible to measure actual shoulder setback from your friend's sizing operation? To my eye one of the cases looks longer.... have these been trimmed a lot?

al
 
alinwa said:
And to expand on what Bob's saying.... the difference in distance between the two lines has me totally confuzzled.

Is it possible to measure actual shoulder setback from your friend's sizing operation? To my eye one of the cases looks longer.... have these been trimmed a lot?

al
Click to expand...

The difference between the lines on the cases also me puzzled, Some of the cases have only one line and some lines do not go all around the circumference, are at randon places along the length of the neck, some cases have a line all the way around and a second line only partially around on the thin side, some have only have a partial single line starting to develop which I think discounts that the cause is a die or chamber defect issue which should cause all the markings to be identical. The cases measure the same at the shoulder, they're just laying flat side by side on a paper towel over carpet so I could get some contrast in the pic to make the lines more visible, so yah, they appear different lengths due to the uneven surface they are placed on. Don't know the history of these cases, how many times they have been trimmed, or even if they have been always sized with the same die or shot from different rifles. Knowing him they wouldn't be trimmed any more than absolutely necessary to chamber and don't know his die set up or it they are full length sized or neck sized. Neck wall thickness varies around the circumference from .011" - .0125", pretty normal for winchester .223 brass. I'll ask him for more details if he's at the range this weekend, he usually is.:)
 
Marc: If he's sizing these cases using dies with a standard-type expander ball, that is probably adding to the problem. Even with good lubrication, these expanders can really pull on the necks when the case is drawn back over them, exacerbating brass issues that would normally not show up when using a bushing die and no expander. Add to that the continual work hardening of brass that's been fired many times in a standard chamber and the weak spots are going to show up pretty quickly.

Check the neck o.d. of a loaded round. Then check the neck o.d. of that case after it's been fired. Now, remove the expander from the die, run the case into it and measure the o.d. of the neck. Now run another case into the die with the expander installed and figure out how much the neck is expanded when it's drug over the expander. Then add in how much additional it's expanded when a bullet is seated. Add al these figures up to see how much actual movement the neck makes during one firing and reloading cycle.....whew! ;)

That's a lot of movement for a .012-.013 thick case neck. :eek: -Al
 
neck problem

If it were mine I would try bushing dies. I had a neck splitting issue with a 22-250 stopped it with bushing dies.....Just my thoughts
 
Just talked to Pete, he informs me that he has been neck sizing these cases using a lee collet die. Anyway he is starting off with a new batch of brass and is going to keep notes, measurements etc to see what the new batch does.
 
Help diagnose Case neck

Even with a gas gun He should be neck turning
Neck turning will improve his accuracy and help solve his problem.
I would neck turn a case fire it and send it to harrels for a bump neck die.
I would also recomend seating with a wilson or a competition seater die.
.
 
Lee dies are usable and will get the job done, however they are an economy die and as such , are often not well finished inside. Sharp edges
could shave brass and eventually thinning, leading the way to stressed areas.
The cases shown also appear to be tumbled or polished,and some info
is obscured which might be helpful in a solution
 
Respectfully disagree...

Bob Kingsbury said:
Lee dies are usable and will get the job done, however they are an economy die and as such , are often not well finished inside. Sharp edges
could shave brass and eventually thinning, leading the way to stressed areas.
The cases shown also appear to be tumbled or polished,and some info
is obscured which might be helpful in a solution
Click to expand...

I've been using Lee dies for over 30 years and have yet to find a quality fault with their product; or have any of my friends that use them. No...they are not on the order of custom dies made for a custom chamber, nor the quality of competition dies from some of the major manufacturers. But for their cost, they are a great value for the majority of hand loaders. As a matter of fact, their collet die systems produce some of the most accurate brass of any die...including custom dies.

No...I don't think Lee dies contribute to damaged brass...no matter their economical cost.

virg
 
Use a "control" case

Keep a case (same case) separate when reloading and load it without any sizing, Just knock out the primer, replace the primer, charge the case and drop in a bullet. Shoot it along with the others that were normally loaded. If this case shows up with a ring on the neck something is awry with the chamber/case fit.

I suspect the difference with the rings is related to variance in seating depth over the life of the cases or variance in the sizing length of the neck.

Blacken the neck of a dummy round (sized and loaded with a bullet) using a butane lighter. Chamber and extract the round and look at the neck. Maybe that will shed some light....
 
Wilbur said:
I'm past curious as to what the cause is/was ??????????
Click to expand...

Beats me. Don't know if it's possible but was entertaining the idea that maybe the case neck was gripping and sticking to the chamber neck upon firing and staying there and the body of the case not gripping the chamber wall and going back against the bolt face and stretching/separating at the neck rather than the usual separation at the case head. Your guess is as good as mine.
 
If he's using a Lee Collet die and only about 1/3 of the cases are showing this problem it might be that the cases showing these marks have thicker necks than those that don't. In the past I've used these dies and found that they'd mark the case necks fairly badly unless the collet was polished some to remove roughness.

Just a thought.
 
Ten years ago I was checking out some Winchester .220 Swift brass to load. The case wall run out was .0015 or less on all that lot of brass.

But when I lightly turned the necks I found several bands of thinner brass at 90 degrees to the neck length . I turned the necks to .2565 before this disappeared (from .259 aproximately).

I believe that Winchester uses an extrusion process to form this brass.
The necks remain quite hard and possibly differ in hardness also.


I have an article by AJ Walker in Shooters News Oct 1997 where he describes the same thing in much fired neck turned 6 PPC brass .


Glenn:D
 
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