Teach me about incipient case separation

[warhwkbb]

In the pictures attached, I have some 30-06 brass that have been reloaded and trimmed between 2x and 4x.
These have all been shot in a Garand at moderate velocity (2620fps). I noticed a shiny ring around the brass 1/4" from the rim. Most of my '06 ammo has this.

I have several questions. First of all, is this the beginning of case separation? Or is this just showing where the chamber contacts the case during firing?

I made a scratcher from some small wire and used it to check the inside of the case for resistance at the point of the shiny ring. Nothing could be found that would indicate any deformities inside the case.

Am I worried over nothing? How many reloadings should a typical case last in a Garand?

 

[rcmodel]

If you can't feel a stretch ring inside the cases?

It isn't stretching.
If it isn't stretching, it isn't breaking.

What you are seeing is the end of the thicker case web and it expands more to fit the chamber from there foreword.
The sizing die burnishes it more there when you resize it.

Nothing to worry about if you can't feel it inside.

rc

 

[Grumulkin]

On the one case you can see the shiny ring that starts before complete head separation; i.e., it's incipient head separation. Also pictured is a case with a complete head separation with the wire (a paperclip) I use to check for incipient head separation.

What you will feel with the bent tipped wire, is a little dip in the inside wall of the case above the web. As stated above, if the wall is perfectly smooth inside, then there is no incipient head separation. Personally, I'm a bit suspicious about the shiny ring on your cases. Are you SURE there is NO irregularity inside the case at that point?

Also, 4 or 5 reloads is probably all you'll usually get out of Garand cases.

 

[ranger335v]

Dictonary: in·cip·i·ent (¹n-s¹p“¶-…nt) adj. Beginning to exist or appear.

In other words, if you can see signs of an impending head seperation that's in·cip·i·ent.

 

[rcmodel]

Maybe so, maybe too.

But if you throw away every case with a burnished ring where the case web ends, and no matching stretch ring inside it?

You are going to be buying an awful lot of new brass and shooting it one time!

rc

 

[Walkalong]

What you are seeing is the end of the thicker case web and it expands more to fit the chamber from there foreword.
The sizing die burnishes it more there when you resize it.

Nothing to worry about if you can't feel it inside.

Like this.

But if you throw away every case with a burnished ring where the case web ends, and no matching stretch ring inside it?

You are going to be buying an awful lot of new brass and shooting it one time!

Exactly.

 

[ranger335v]

"But if you throw away every case with a burnished ring where the case web ends, and no matching stretch ring inside it?"

Granted, but anyone presuming every burnished sizing ring he sees is an incepient sign of a coming seperation is misconstruing what he's looking at isn't he? Fact is, the current fad of tumbling every case every time it's used so it's purty glosses over real case stretch rings anyway!

 

[W.E.G.]

Your resizing method has much to do with longevity of brass.

What kind of case gage are you using to ensure that you resize the brass to the correct dimension?

 

[warhwkbb]

What kind of case gage are you using to ensure that you resize the brass to the correct dimension?

I use L.E. Wilson headspace gauges. My sizer die is set for the middle of the headspace range.