Reloading question. brass issue.

[YBPS]

.264 Win mag, new nosler brass, 140 VlD, 65.2 gr Retumbo, 3280 FPS

What could cause this dent in the brass?


This is the third time this has happened in about 100 rounds fired.

 

[Muley Buck]

At what stage is that piece of brass at? Are you saying that is the result of firing a normal looking round?

 

[UtahJimmy]

I would say something on the brass when you sized them? I had a piece of corn media stuck to this case that I didn't see until after I released it from the press.

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[Neverenoughhntn]

First I’ve seen that...Assuming that’s the result after firing and not resizing, it seems to me like you’d have to have something floating around in your chamber. A while back, I ran a nylon brush through a barrel and it left a couple bristles behind. I noticed it immediately, but I imagine the result would’ve looked similar to your pic.... no idea what it’d be otherwise, but then again there are plenty of guys that know a lot more than I do.

 

[jorgensen.travis]

I'm no expert on the 264, but that seems to be fast. Is that in SAAMI specs?

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[jorgensen.travis]

This is from Hodgdon's website. Note the 26" barrel length and speed. I think you're way over pressure.

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[YBPS]

Yes.... result of a fired round. I know the brass was in good shape prior to being fired. No other dents on any of the other cases. You would think that extra pressure would push out. Not in? My barrel is 29" and there are no signs of pressure.

Interesting from the hodgon book. Berger list 65 start and 68 max. Have shot to 69 and there was pressure. But nothing crazy.

This is not a factory chamber. ...

 

[WV Mountaineer]

I'm simply stumped

 

[Muley Buck]

Very strange indeed...

 

[ramont]

I believe that either your cartridges are under pressure by quite a bit or your neck tension is so light that the bullet is moving before the case expands in to the chamber walls. The dent is created by the combustion gasses that have moved back in to the area of the shoulder. You can see gas burns under the shoulder and in the dent.

 

[Stid2677]

Are you crimping? How many firings on the brass? I think that the brass has become work hardened and is the neck is too tight. The hardened brass is not expanding and hot gasses are being forced back between the neck and the chamber. This would explain why only a couple of the more hardened cases deformed.... Might be time to anneal. My best guess anyway.

 

[Wapiti_Harvest]

Are you sure this happened after firing? The dent is the picture looks classic for over lubing the case while sizing. Look for it in a reloading manual and you'll see what I'm referring to...
Hope it helps

 

[akspudus]

Those dents do look like the classic dents caused by excessive lubricant on the case or in the resizing die.
They are safe to fire and the dent will fire form out.
However, you mention that you suspect that it was caused during firing. Do you have some pictures of the cases after foreign and before resizing?
I have seen dents caused by the extraction/ejection process.
Another trick is to use a sharply to mark the case. Index the mark on some reference point on the rifle (or place the mark straight up). Fire the cartridge and see if there is any correlation or consistency as to where the dent shows up. If there is a defect in the rifle’s chamber, the dent will form in the same spot in relation to the index mark.

Hope this helps.

 

[YBPS]

I believe that either your cartridges are under pressure by quite a bit or your neck tension is so light that the bullet is moving before the case expands in to the chamber walls. The dent is created by the combustion gasses that have moved back in to the area of the shoulder. You can see gas burns under the shoulder and in the dent.

I think you are on to something here.... I am using a Type S bushing die. I think I need to try a little tighter bushing. Like I said before, this was actually a new case. For the people asking/thinking this is a sizing issue, I can assure you there is no possible way that this happened during the sizing process.

 

[Tod osier]

I was intrigued and searched this yesterday (sorry for not following up until now). There are cases of this exact thing happening (google: "dented cases after firing" and look at images to link to relevant threads). Looks like the suggestions regarding gas escaping the neck seal and denting the case from the outside are on the right track. The couple I read yesterday seemed to be related to light loads and not being enough pressure to seal the neck (not your case here).

 

[rayporter]

I have had that happen with a light bullet and a very slow powder.

pressure does not build up and seal the neck.

 

[wjohnson1983]

Those dents do look like the classic dents caused by excessive lubricant on the case or in the resizing die.
They are safe to fire and the dent will fire form out.
However, you mention that you suspect that it was caused during firing. Do you have some pictures of the cases after foreign and before resizing?
I have seen dents caused by the extraction/ejection process.
Another trick is to use a sharply to mark the case. Index the mark on some reference point on the rifle (or place the mark straight up). Fire the cartridge and see if there is any correlation or consistency as to where the dent shows up. If there is a defect in the rifle’s chamber, the dent will form in the same spot in relation to the index mark.

Hope this helps.

This is the only time I've seen a dent like that as well. Though not as severe in the picture. OP says from a fired round though, so it's a new one on me.

 

[ramont]

The manufacturer recommends that the S bushing be sized a few thousands smaller than the fired case neck (can't remember the exact amount but it's in their instructions), obviously you can sneak up on that bushing size but it sounds like you need a little more neck tension. Typically I use a bushing that is about .003" smaller than the outside neck diameter of my fired cases.

 

[jorgensen.travis]

Obviously there are bottleneck cartridges that run on much lower pressure and never have this issue. When we're talking about pressure being too low, we're talking about pressure being too low for Ratumbo's super slow burn rate right?

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[treillw]

.264 Win mag, new nosler brass, 140 VlD, 65.2 gr Retumbo, 3280 FPS

What could cause this dent in the brass?


This is the third time this has happened in about 100 rounds fired.

Are you seeing any carbon/powder burn on the brass anywhere but on the neck? I had a problem while fire-forming brass earlier this year that is kinda of similar, but I didn't have any big dents like you're getting. My brass was shrinking in length after firing by about .015". It blew my mind at first.

With the new brass and short cheap bullets I was using to fireform, there wasn't a "seal" to direct all the gas down the barrel. Gas was escaping and compressing the brass. I solved the issue by loading the bullets to lands to create a false shoulder and direct the gas down the barrel.

If you have any unfired brass left, measure the shoulder dimension and see if the fired brass is expanded or compressed.

Once the brass is fire formed, your bushing size may be adequate.