223 Case Rupture - Headspace Discrepancy?

bryandg:

The dull ring i get with once fired factory brass is about the same distance down from the neck as the original posters images. 1/2 way between base and neck. An obvious stretched area. Only seen on once fired brass.

Brass with the stretch mark 1/2 way down always gets pitched into the recycle can. I crush it with a pair of Channel locks that are on the bench.

I don't reload my 223 brass more than about 3 times except for some workup test brass that i keep separate from the rest. That brass i pitch after 5 loads.

I have seen a ring near the base of some 2011 once fired Lake city, and cut those in half to look for a problem. No problems found, checked un-fired ammo form same lot of m193, and a few of them had the same ring in new condition. Also just looked at some bulk M855, and several of them also have the same ring.
 
Sometimes a separation that far up the case on a semi-auto is a gun running out of time. The brass is stretching more than it should AFTER it is fired. Even overly hot loads will cause this. The bolt is ripping the case out of the chamber before the case has shrunk back down and is still kind of stuck in the chamber.
 
Maybe just dumb luck I have, I routinely reload at least 10 times (even 20 times) before having to retire a batch of brass. That includes several gas operated semi autos; sks, M1, M1 carbine, fn49, and vz52. don't have an AR yet, but soon will. I don't believe it will be any different though.

Over gasing tears the rim. Never have seen head separation because of it.

BTW, AR has floating firing pin. Head separation like this one worries me. It is a prerequisite for out-of-battery slam fire. Same goes to sks, M1, and M1 carbine. I will be extra careful examining the brass. Any sight of imminent head separation, the whole batch of brass will be rotated out.

-TL
 
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The HK G3 family has a similar 'problem' as the head moves back as the pressure is still high, causing the neck to grip at the same time, stretching the case .That limits the reloads to about six.
 
Braing wrote:
I wouldn't buy or collect used rifle brass any more than I'd pick up that half empty bottle of tequila next to the doorstep.
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Excellent comment and advice...

Many years ago, shooting on one of the service high power rifle teams, I had an out of battery fire...and the only thing that saved my eyes, if not my complexion, was a pair of large lens, Bauch and Lomb shooting glasses that our team armorer and coach demanded that we wear. They saved my eyes, and probably my life based on the nicks and damage to the lenses.

Best Regards, "Ears and Eye protection - On" Rod
 
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mete said:
The HK G3 family has a similar 'problem' as the head moves back as the pressure is still high, causing the neck to grip at the same time, stretching the case .That limits the reloads to about six.
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Passed 10 loads and still going here. Proper roller size is the key. Mighty strong Israeli military .308 brass also helps. I have a ptr91.

-TL

Sent from my SM-G930T using Tapatalk
 
'problem' as the head moves back as the pressure is still high, causing the neck to grip at the same time, stretching the case .That limits the reloads to about six.
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I believe we would be looking at another set of problems if that was true. I believe the limit to the number of firings would be limited to one because I do not believe the neck would still be connected to the case shoulder/neck juncture.

F. Guffey
 
This thread reminds me of another recent one. A member commented that his pistol cases grew shorter over time. It illustrates that there are many forces and actions. Pistol brass is worked pretty hard in loading, not so much on firing. Rifle brass is worked in entirely different ways, and imo, worked harder.

The gas op semiautomatic rifles yank the brass out by the base.

The long and short is that a solid action with neck size only, a properly fitted chamber, and realistic loads will will last until it won't hold a primer, o the neck splits. The brass isn't being worked significantly.

Reloading and using in a semiautomatic works the brass a lot more, and being a bit out of spec any direction will increase the wear a bit. Brass can only be worked a finite number of times before giving out, maybe catastrophically.

That's really all I have to say, is that reloading for one is obviously workable,
. My choice would be to use good brass and dump it after a few times. I'm really cautious.

Anyone can stretch that our many more times, but inspection well between rounds.

Btw, someone mentioned that brass was made by extrusion. No, it is drawn. There is a difference.
 
Well Guffy, You would be wrong. I have used a ruptured case extractor many times (New brass) and never pulled just a neck out. All separation was below the shoulder. Somebody just had a Thread going about stretched brass(I think 7.5 Swiss) and it was the press doing it because the expander ball was too large. It really does not take much to stretch brass, especially if it is hot.
 
223 neck

Mine fired in Savage Axis The next round jams into the remaining neck in the chamber. Easy extraction.
th_FCBrass1997.jpg
[/URL][/IMG] Brass washed in vinegar and in storage for a long time will get brittle and do the same thing.
th_223LC86Brittle_002.jpg
[/URL][/IMG] These fired in M16. Both my photos.
 
Using acidic cleaners for your brass? Neutralize with baking soda and then rinse very well to remove any residual metallic salts.

This is something to remember. Brass is zinc alloyed with copper down to the molecular level. It's far more complicated than mixing salt and sand.

Here is the reason I get rid of old brass. Tarnished, stained, corroded brass is breaking down molecularly. Zinc is separating, both metals are oxidizing, and the whole package is getting porous and weak, and once in a while it causes cases to fail. If any of you have ever fired REALLY old rounds and found that a number split, it is possible that the brass was just breaking down chemically to some degree. Any round that you find that's dark you can't recognize it as press and it has spots of green probably should be set aside.
 
'problem' as the head moves back as the pressure is still high, causing the neck to grip at the same time, stretching the case .That limits the reloads to about six.

I could have sworn he said the neck grips the chamber and then I said if that happens I believe the neck separates from the case. But that is not what happens. The case expands and locks onto the chamber; after that it gets so complicated most can not keep up with it. And then there is that compulsory memory work; goes something like the firing pin strikes the primer then everything takes off for the front of the chamber including the bullet, case and powder and collides with the shoulder of the chamber. And then somewhere in there reloaders are trained to say; “and then the bang”.

A much disciplined reloader gave me 60 7mm Remington mag cases. It had nothing to do with not appreciating the cases but I wanted to know where he got the cases. Instead of answering me he wanted to know why I would care. I explained to him the shooter/reloader had some bad habits he needed to be aware of. The answer was “too late”, he died of a heart attack; point? His case necks were locking to the chamber. I had the cases and no one knew where the rifle went.

F. Guffey
 
I'm not sure I run on F.Guffey's level, but I get what he's saying.

30+ years ago I was building/tuning AR rifles to better suit the rounds being fired through them,
and to this day eyes glaze over instantly when you start the conversation about gas pulse pressure AND duration combined with pulse timing.

Direct gas impengment firearms are MUCH more particular about gas operation than piston rifles,
But suprisingly, they are easier to tune in most cases...

It's no secret, the shorter the barrel/gas tube, the more issues you will have, both with operation of the rifle, but with the brass if you choose to reload, which isn't as widely known.

Short tubes will unlock that bolt LONG before it probably should be, and cause all sorts of issues, if not in the short term, it will most certianly cause issues in the long term by eroding bolts/carriers/gas rings, shaving/rounding over the locking lugs, and slamming that bolt/carrier to the rear WAY to hard...

Even in bolt rifles, way "Hot" loads will hammer the chamber out much faster than it should erode with 'Standard' pressure rounds.
 
This is once fired PMC brass. Unfortunately I do not know which of my rifles it came from. I have a bolt, and very different semi autos. This is the first case I ever resized and pushed a bullet into. It has no primer or powder. I keep it on my desk. Its finish was all shiny and clean. After many months of picking it up and twirling it and fiddling with it as I sat at my desk the oils in my hand revealed this strange ring:

IMG_1682.JPG


I ran a paper clip with a hook inside of it and there are no detectable edges or changes in the brass.

In my opinion it is just some type of change in the surface, either during extraction or resizing that allowed oils and dirt from my hand to work into that spot. I have other cartridges that are fully loaded from that same day that have not been handled and are uniformily shiny from top to bottom and look brand new.
 
I cant repeat it often enough. Get a jewelers loupe, twenty to forty, and keep a magnifying glass on hand, and get some reader glasses. You may be able to learn something about that particular shell.

I once got a package of Lake City brass in .308 that had cannelures at about that place...
 
In response to Jeephammer's post.

Alot of the negatives could be quashed with an adjustable gas block.

Found out all about just how hard the gas system can beat up the gun and brass when I put a suppressor on mine. Dropped an adj gas block on there, found settings for shooting with and without the suppressor on there. Made quite a positive difference in the way the gun operates. No longer a massive pulse of gas violently unlocking the bolt and slamming the carrier to the rear. More of a gentle but effective push now.
 
Well Guffy, You would be wrong. I have used a ruptured case extractor many times (New brass) and never pulled just a neck out. All separation was below the shoulder. Somebody just had a Thread going about stretched brass(I think 7.5 Swiss) and it was the press doing it because the expander ball was too large. It really does not take much to stretch brass, especially if it is hot.
Click to expand...


'problem' as the head moves back as the pressure is still high, causing the neck to grip at the same time, stretching the case .That limits the reloads to about six.
Click to expand...
I believe we would be looking at another set of problems if that was true. I believe the limit to the number of firings would be limited to one because I do not believe the neck would still be connected to the case shoulder/neck juncture.
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Explain what? He said the neck locks to the chamber and I said it is not likely the case can be pulled apart while holding the neck. And then there is that story about pulling the shoulder forward with the sizing ball when the ram is lowered; and no one can measure before and again after.

F. Guffey

In response to Jeephammer's post.

A lot of the negatives could be quashed with an adjustable gas block.
Click to expand...

And then there are pulse dampeners
 
And then there is that story about pulling the shoulder forward with the sizing ball when the ram is lowered; and no one can measure before and again after
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.

Well I exaggerated that one a little, I should have included the part about one reloader that can and has; that would be me, I can.

F. Guffey
 
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