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  #1  
Old 10-25-2018, 03:38 AM
Oso Polaris Oso Polaris is offline
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Default 223 AI - Case Forming Irregularities

I was fire forming cases for my .223 AI. I encountered something unusual while fire forming factory ammunition. You will note a narrow banded bright spot that equally circumnavigates the entire case (left 3 cases). In some instances this mark on the case was a well defined crease / indentation (right 2 cases). If I had reloaded the cases it would have caused a case rupture/separation. I observed this defect occurring periodically even after changing ammo brands.

At first I thought this my be the result or debris or metal shaving in the chamber that was cutting the brass. However, this can't be the case because the marks were uniform in location and appearance, and wraps around entire width of case.

My hypothesis is that this is a result of gas. The location on case of the bright spot/crease corresponds with where the normal taper of the .223 case and the new 223 AI chamber are the same diameter. When there isn't a tight seal during the crush fitting of the .223 case into the AI chamber (at the neck/shoulder junction) then a portion of gas escapes around the shoulder. This leaked gas heads back toward the bolt face, finally terminating at the point where the case and chamber meet. The amount of gas blow-back depends on the size of the gap. If enough gas escapes then it gets redirected into the case etching a crease or even cutting the case.


Anyone ever had this happen??? Doors open to any all speculation....

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Old 10-25-2018, 03:49 AM
varmintshooter varmintshooter is offline
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Looks to me to be case head separation. You can take a paper clip and bend an eight inch 90* at the end to feel if there is a crease/grove on the inside of the case where the line is. It is because the headspace is not right.
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Old 10-25-2018, 03:50 AM
Bill K Bill K is offline
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Default 223 AI case fireforming irregularities

You need to seat your bullet out further and engage the lands, so the case sits tight against your bolt face. You are getting a headspace issue and that is causing the ring and what will lead to a case separation at that point.
That should solve your issue, and the case will fireform into the chamber of the AI, then it is just a matter of reloading for the new case in your 223 AI dies. Bill K
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Old 10-25-2018, 03:57 AM
varmintshooter varmintshooter is offline
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The case should index on the shoulder (crush fit) in order to get a good seal and form properly. The bullet need not touch the lands.
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Old 10-25-2018, 08:30 AM
JSH JSH is offline
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I tend to agree with the above on head space seperation.
Some years back when I was playing with a 6TCU I had what you could call false seperation lines. They had been in an ammo box and rattled around, all of them had a shadow of a line all the way around much like yours.

IMHO a slight shoulder crush is more desirable than jamming bullets in order to keep brass back against the bolt face. Some times depending it can't be done.
That is when I try necking up one caliber, then back down until the bolt will close snuggly.

Also a good application for cast bullets. Most are over sized compared to jacketed and can be "jammed" some what easier. I tend to think pressures don't get all wild either.

And, even if you had used COW to fire form and your sizing as done above, your brass would still have not formed properly. It may have formed with less visible sign than above, but will none the less still have very short case life.
Jeff
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Old 10-25-2018, 02:19 PM
Bill K Bill K is offline
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Default 223AI case forming irregulaties

Quote:
Originally Posted by varmintshooter View Post
The case should index on the shoulder (crush fit) in order to get a good seal and form properly. The bullet need not touch the lands.
Generally that is the correct way, but when he or you are forming AI case with the standard 223 case, the shoulder can not reach to make full contact, there fore you use the bullet, just touching the lands to hold the case back on the bolt, so the shoulder can form into/onto the new shoulder angle. Bill K
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  #7  
Old 10-25-2018, 02:47 PM
SEM SEM is offline
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More info type of rifle? guessing AR since you referred to gas, apparently using FACTORY loaded ammo is not successful you probably should find some once fired 223 brass and start there, A false shoulder is the best way to prevent separation. Bills idea works fine too if you don't wish to mess around with the extra steps necessary to make a false shoulder.

P.S. I keep forgetting to mention CLEAN the chamber of all solvents and oils BEFORE trying to form any case. 91% rubbing alcohol and a swab just before firing and after several dirty rounds

Last edited by SEM; 10-25-2018 at 02:56 PM.
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  #8  
Old 10-25-2018, 04:12 PM
flyrod flyrod is offline
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Quote:
Originally Posted by Oso Polaris View Post
I was fire forming cases for my .223 AI. I encountered something unusual while fire forming factory ammunition.
Factory ammo is pretty sloppy in an AI chamber. It looks to me like those cases are stretched out and are scrap. If you cut one open you'll see a thin spot in the case wall where the brass is stretched and ready to split in two.

When you fire those rounds, they are pretty far forward in the chamber when they go off. The front part of the case seals against the chamber and the back part slides backwards until it stops at the bolt face (stretching the case in the middle). There are ways to address this when loading your own ammo, but for factory stuff there's not much you can do. If the extractor hook is high tolerance, then it might be able to hold the case against the bolt. But this may cause other problems if the round can get in front of the hook when chambered. I've seen some people remove the ejector spring/pin in remington style actions. This might help some, but the firing pin will still tend to drive the round deeper into the chamber when fired.

The best solution is probably to load your own ammo.
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Old 10-25-2018, 05:12 PM
varmintshooter varmintshooter is offline
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When a 223AI chamber is cut a standard 223 will fit in it but it should be tight not sloppy. That is why they take about .006" off the back of the barrel when the chamber is cut. I have been wrong before but I don't think I am wrong on this.
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  #10  
Old 10-25-2018, 05:22 PM
Daryl Daryl is offline
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Normal case head separation, but 1/2 way up, common with poorly chambered barrel.

This separation is due to sloppy AI chamber with barrel not set back properly

or reamer run in too deeply.

Do not attempt to reload that brass. Throw it away. Neck your .223 brass up to .257 (.243 might work), then down to hold a .224" bullet with crush fit in chamber. Problem solved - for you.

A Hornady expander button is good for this due to being as hard as the back of God's hand, as well as being nicely tapered- thus, a .243 or .25 Bob,.25/06, etc die set would be perfect for necking up the .223 brass.
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Last edited by Daryl; 10-25-2018 at 05:26 PM.
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