Air dents as opposed to lube dents

Guffey:
My premise of the air flow is opposite to what you have stated. I maintain that as the case is being raised into the die, the outside trapped air is pushed upwards and then vented down the case neck for the split second that the neck is open before sizing begins and then outwards through the open primer pocket, thereby closely equalizing outside and inside pressure. Since we can't observe the air flow, who can say what is actually happening? But the bottom line is that the process works and the denting has been eliminated.
 
wogpotter:
Well not really that much of a worry situation, but rather an unusual situation looking for solutions and drilling a vent hole could certainly be one. It happens that this SAECO sizing die does have a rather long decapping pin, allowing the primer to extract before sizing begins, and the solution may not work with a die having a shorter pin. I guess that makes sense, sizing would begin before the primer could be extracted, thereby leaving excessive air pressure on the outside of the case resulting in the presumed air dents. That is what was happening before higgite came up with the idea to further lower the decapping pin to give the air an escape route and relieving outside pressure.
 
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I maintain that as the case is being raised into the die, the outside trapped air is pushed upwards and then vented down the case neck for the split second that the neck is open before sizing begins and then outwards through the open primer pocket, thereby closely equalizing outside and inside pressure.
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It is not possible to have it both ways, I have neck sizing dies, I do not use them for neck sizing but I have them JIC. Then there is neck sizing with a full length sizing die. For that to work the die must start sizing the neck before the die starts sizing the die body; meaning the neck of the case is the first part of the case to get sized.

F. Guffey
 
No argument there. The neck is supposed to start sizing before the body of the case starts to size. And of course it can't be both ways, talking about the air flow I presume, but one way or the other, if only we could tell which by observing the air flow. But it makes little difference since the desired effect has been achieved with the mysterious denting being eliminated.
 
I think the issue is, especially with cases with straighter side walls, or slightly tapered cases that have expanded far enough, do you start to get a case body seal down near the sizing die mouth before the neck is all the way resized, thus trapping the air between the two sealed positions. I have illustrated this below. You can see a vent is then needed to avoid compressing a fair amount of air if the press is moving too fast for it to bleed out past case lube at the bottom or the neck surface imperfections at the the. It would never happen with a tapered case like a 30-30, but could happen fairly easily with most Ackley Improved cartridges if no vent is present.

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Yes I'm sure what you describe is exactly what had been happening (starting to get a seal), it is a rather tight fitting die. Just strange that the SAECO die lacks a vent port. But with the current die adjustment apparently allowing trapped air to escape momentarily through the neck, sizing speed is no longer an issue, can either be fast or slow with the Winchesters. The other heavier cases were never affected. And thanks for posting a basic .jpg, my Samsung gadget does not work with the photobucket postings so I miss a lot of photos.
 
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Actually shouldn't have said that adjusting the sizing die made the difference since that remained the same. The key element seems to be that by lowering the decapping stem, per suggestion by higgite, the primer expells right before the case neck enters the sizing section of the die, thereby allowing enough trapped air to vent through the neck and outwards through the open primer pocket to prevent the apparent air dents with the Winchester cases. At least something is working.
 
Unclenick said:
Curious that a die setting would matter to it if that principle is correct. I'm still missing something.
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Doesn’t quite add up to me either, Nick. Like I said, it was a shot in the dark, but it seems to have had a positive effect. Maybe it has something to do with moving the expander button farther down in the die when the decapping stem was lowered. Possibly the expander button and neck sizing portion of the die were too close together, putting more pressure on the neck/shoulder than the Win brass could take at speed without lubing that portion of the case? Wonder if the Win brass is thicker than the other? I dunno, still guessing.
 
The Winchesters are the lightest of the bunch, suggesting that previously they couldn't hold up to the maximum built up air pressure and most of them dented. With the current decapping rod setting, it seems that enough air pressure is released to prevent the denting.
 
One additional comment worded slightly differently, hoping to convince everyone what I think has to be happening. By turning the decapping rod down further, for a brief period of time, immediately following primer ejection, the case neck has not yet started to enter the sizer, thereby allowing a complete passageway through the open case neck and out through the open primer pocket, which is sufficient to allow enough air pressure to escape for the duration of the sizing stroke and eliminate air denting. Right when the primer is ejected, the expander button is well within the case near the bottom and would not block or affect air flow in any way. Note that following primer ejection, going no further with the case into the die, the case can be withdrawn and verified that case neck sizing has not yet begun and the open passageway exists. Seems rather straight forward.
 
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One additional comment worded slightly differently, hoping to convince everyone what I think has to be happening. By turning the decapping rod down further, for a brief period of time, immediately following primer ejection, the case neck has not yet started to enter the sizer, thereby
Click to expand...

In the absence of comments I will assume I am the only one that can keep up with that much detail. If I measured the protruding primer punch from the bottom of the die I could tell you when the neck started in to the neck sizing part of the die.

I have purchased dies with vent holes that were plugged; I have dies that do not have vent holes. I am the only reloader that cleans dies with a towel on a dowel. When cleaning dies with a towel on a dowel my color of choice is white. It is much easier to tell when the die is clean when the towel is white.

F. Guffey
 
I was expecting more comments so your comment is certainly worth a smile. I guess I was trying to cover all details in a single sentence.

I assume your second paragraph represents the code of wisdom to live by for the day. :)
 
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With the towel on the dowel
You clean out all that's foul
Load some birdshot for the gun
And go get yourself some fowl.


CB,

I suppose, if the sides of the case meet the die ahead of the case mouth, that letting a little air flow through the primer pocket would lower the air quantity inside a little bit, but I'm having a hard time imagining that makes a lot of difference in and of itself as you are talking about changing a fraction of the total air volume that way. If the decapping adjustment is actually making a difference, it makes me think something else is going on. Is your die one where the expander is up high and is in contact with the inside of the neck when the case mouth starts to resize?
 
No the expander is not at all high in the die; located on the extreme lower portion of the decapping stem as usually positioned on sizing dies. So do not think the expander enters into the situation at all.

Also good wisdom for the day.
 
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Is your die one where the expander is up high and is in contact with the inside of the neck when the case mouth starts to resize?
Click to expand...


The step sequence is something that is most difficult for most to keep up with; but if that happens I would expect to see a case neck folded back thought the case shoulder; or a case with a missing neck after the ram was lowered.

There was an attempt to reduce the ‘clunk; time when lowering the ram. The sizing ball/expander was located high on the primer punch/expander ball assemble. Then there were those reloaders that punched the primer first then raised the neck sizing ball to reduce the travel distance.

If I thought the die was being sealed at the top I would use a die friendly rubber tipped air nozzle to pressurize the die and then stick the top of die into a bucket of water; and then check for leaks.

F. Guffey
 
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What I had in mind was some expanders are set closer to the top of the die body than the traditional type down at the deapping pin chuck. The idea is that when you then withdraw the resized case, the fact a little of the case neck is still inside the neck portion of the die when it starts to engage the expander will make that withdrawal start straighter, thereby mitigating the expander pulling the neck off-axis.

It simply occurred to me that if that were happening, it forms another air escape path blockage. Should that happen? No. Air should be escaping past the threads that the decapper is held in place by. These aren't class 3A threads, after all, so there should be plenty of gap in the thread helix for air to bleed past. But it's possible that if the press is operated fast enough, and especially if there is oil or grease present in the thread, that the air still won't be able to squirt out past the threads fast enough to avoid making a little added pressure. Not enough to dent the case, but enough to raise the amount of air trapped in the space I illustrated.
 
Yes I was aware of what you were getting at, should the expander be high up on the rod. Have never seen one like that but I guess they exist.
 
Yes. The Lee EZ-X expanders are like that and can be adjusted up in that neck fitting range. I've had better luck either mandrel expanding after sizing or using a carbide expander plus dry lube to minimize neck drag.
 
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