Incipient Head Sep on first firing


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RavenVT100
July 27, 2007, 10:10 AM
I have some once-fired LC brass that I'm reloading. Headstamped 02 for 2002 manufacture.

One of them, having only been fired once in a rifle that is headspaced correctly (and does not currently have headspace issues) has that telltale bright ring right above the case web.

I've only been doing this for about six months and haven't ever seen this. Is it normal for brass to occasionally be "bad" like this?

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Walkalong
July 27, 2007, 10:14 AM
If it has been resized to much(shoulder set back too far) it can seperate or nearly seperate on the first fireing. Headspace caused from sizing, not the chamber.

RavenVT100
July 27, 2007, 10:16 AM
I think you may have misunderstood--this is once fired brass. Meaning this ring showed up after it was fired, after having been manufactured at the factory.

It wasn't something I resized and then shot.

mrkubota
July 27, 2007, 11:56 AM
reloading 'factories' have been known to set shoulders back too far as well...

Put the ammo through a case gauge or a set of calipers to check it's proper measurements.

What caliber ammo is this?

RavenVT100
July 27, 2007, 12:29 PM
Federal XM193 (5.56mm), Lake City, Headstamp LC 02 (Nato).

Bad Flynch
July 27, 2007, 12:42 PM
I have seen this before in a once-fired case; it must have slipped by the QC measures at the armory. However, there are no requirements that this brass be reloadable, either.

JDGray
July 27, 2007, 12:52 PM
Had some factory new .32 cases split on first fire. Was Magtech, if I remember right.

snuffy
July 27, 2007, 12:58 PM
One of them, having only been fired once in a rifle that is headspaced correctly (and does not currently have headspace issues) has that telltale bright ring right above the case web.
You have no way to know that unless you fired them all the first time. Then, if it WAS your rifle, did you actually have the headspace checked? Or are you assuming it is correct because it was produced in a factory? Also, you see a bright ring, is there a corresponding groove on the inside of that case?

I'm not trying to be a smart a##, just trying to get everybody on the same page here.

RavenVT100
July 27, 2007, 01:15 PM
You have no way to know that unless you fired them all the first time. Then, if it WAS your rifle, did you actually have the headspace checked? Or are you assuming it is correct because it was produced in a factory? Also, you see a bright ring, is there a corresponding groove on the inside of that case?

I'm not trying to be a smart a##, just trying to get everybody on the same page here.

No, that's perfectly OK, I appreciate the questioning.

The rifle that it was fired in is a build. I used a Bushmaster barrel, Bushmaster carrier and Bushmaster bolt. The barrel and bolt I had Bushmaster check the headspace on before they shipped. The case in question was fired about three months after the build was new, when it had less than 500 rounds through it.

There is not a corresponding groove on the inside of the case that I can detect (I use the 90 degree bent paperclip end method). I'll admit it's made me paranoid about the other cases I have. Is the groove a more reliable indicator than the ring on the outside? I'm going to dremel this case apart and then show you guys the cross section later tonight.

snuffy
July 27, 2007, 01:36 PM
Great comeback! Ok, so we know where we are so far. In my opinion a groove corresponding to a bright ring is MORE of an indication of incipient case head separation than just the bright ring by itself. As was said, one case may have slipped through inspection at the lake city arsenal. That means the rest are probably ok.

Sectioning the case with a dremel will surely show any stretching at the web.

I had a problem with a .308 just recently. The bright ring tipped me off that something wasn't right. About half of the cases that showed the ring, I could feel a groove on the inside. A case gauge from Wilson, told me I had the sizer die down too far for that Savage rifle, about 12 thousandths too far! So much for die instructions that call for setting sizer dies to touch the shell holders! :fire: :cuss: :mad: Setting the shoulder back THAT far will cause that real quick.

Ol` Joe
July 27, 2007, 06:02 PM
Is the ring at the point the web and case wall meet?
I think you are seeing the pressure ring in the web area of your case. When the die sizes the case at this point it polishes the brass a bit and it can at times be mistaken for a sign of seperation. If a sharp wire doesn`t detect any grove and cutting a case doesn`t show any stretch this is likely what you are seeing. The stretching I`ve seen indicating insepient seperation has been a tad higher on the case wall then at this point. The cases also were firede more then one time.
Here is a web site that shows the stages of seperation and other brass related problems.

http://stevespages.com/diagnosingproblems.html

peterotte
July 27, 2007, 06:52 PM
RavenVT100

All the replies above are valid and wise responses. However, bright rings can also show up for reasons other than imminent case head separations. My hornet does this to me all the time and I still get a fright when I see it. I do not know what causes it but in my case, it is not case stretching or any kind of damage.

It is possible that in your case, you had a very dry case and chamber, preventing normal case set back onto the bolt face. (No harm done). I have a reloading technique that I will hesitate to recommend to others since there is a controversy involved, but I actually lube my loaded cartridges. However, an OILY chamber can cause dangerous excess pressure due to diesel detonation of atomised oil being injected into the combustion space around the case neck. Both my rifles have rough chambers and would otherwise stretch the cases to failure after only a few firings.

Hope this is of interest.
Peter

RavenVT100
July 27, 2007, 07:08 PM
I believe Ol'Joe called this one, gentelmen. I appreciate your responses.

I dremeled the case open and the ring is indeed right where the web and body of the case meet. There is no corresponding groove inside the case and the brass is very thick where the ring is. It does not look like the pressure ring that I see when I resize the case, but it's definitely not because of head separation either.

Interesting, I didn't know that a ring like this could show up for many other reasons but it makes sense. Glad I was on the safe side though.

Walkalong
July 27, 2007, 07:10 PM
I believe Ol'Joe called this one, gentelmen. Yep.

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