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Internal Donut on new brass?

SmokyJoe

Sergeant
Full Member
Minuteman
Mar 3, 2011
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Sonoma County, CA
I have some new ADG 6.5 PRC brass that has a slight internal donut or raised rim at the bottom of the neck. These were prepped with a turning mandrel, trimmed/chamfered and lubed with HbN prior to loading. Loads fine until the 156gr EOL hits that donut. Anyone run into this? Possible solutions other than inside neck reaming? I tried running them through with the mandrel again, but the donut remains.

I have two 50ct boxes of this brass, same lot number. First box loaded without issue; second box not so much. The fully crushed case did not present as much resistance as one would think necessary; more than lubed .002, but I don’t recall going gorilla on it. Then again, I’ve never crushed a case like that before.

I may load them with shorter 130 hybrids which would not be below the neck/shoulder junction, fire them, then go through full prep including annealing to see if that helps to smooth things out. I am hoping to avoid inside neck reaming.

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I don’t think it’s a doughnut. What makes you think it’s a doughnut? Did you measure the neck diameter at the case mouth and at the shoulder?
 
I’m guessing something is wonky with your seating die.
My 7 saum adg brass is awesome.
I do open up the necks on new brass with a 1 thou under mandrel before loading.
Also when I turn necks I slightly get into the shoulder as that’s where the meat that can become the donut comes from.
 
I don’t think it’s a doughnut. What makes you think it’s a doughnut? Did you measure the neck diameter at the case mouth and at the shoulder?
In the second photo you can see a raised rim at the bottom of the neck. It is more ‘polished’ where the mandrel encountered more resistance. Maybe donut is the wrong term, but it definitely presents enough resistance to deform/crush the case.
 
Bushing shined up that neck pretty good. Its not upside down is it?
Missed the 'Turned' part.
Reflected light at neck/shoulder junction looks curved. Is it?
Maybe some straight edge pics? Box cutter blade edge is pretty straight.
 
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If it's over annealed you can literally just smash it against the workbench, gotta be a die issue.
 
Screw the mandrel, Full length resize with the button expander that comes with the die installed.

See if it makes a difference?
 
Did you measure the neck thickness?
Neck outside diameter is a pretty consistent 0.2925 until you get about 80% of the way down the neck, where it increases in dia by .0005 to .001”. Then below that it decreases to 0.2925” again. Neck thickness is a very consistent .0145”. I can’t measure the thickness at that raised internal rim with my thickness caliper as the outer stem hits the shoulder, but, I can see it Is raised there.
 
Bushing shined up that neck pretty good. Its not upside down is it?
Missed the 'Turned' part.
Reflected light at neck/shoulder junction looks curved. Is it?
Maybe some straight edge pics? Box cutter blade edge is pretty straight.
The loaded case on the left is only partially pressed into the case. I stopped when the resistance increased. The curvature you are seeing is where the boattail stopped on that raised rim. Still deformed the shoulder slightly. These cases have not been turned.
 
I’ve checked the seating die to make sure it is not interfering with the case and it is not. The crushed case is from too much seating resistance. Checked bullet diameter and it is typical Berger perfection at 0.264”
 
The loaded case on the left is only partially pressed into the case. I stopped when the resistance increased. The curvature you are seeing is where the boattail stopped on that raised rim. Still deformed the shoulder slightly. These cases have not been turned.
if you sized the inside of necks with a neck turn mandrel there’s no way you should be crumpling shoulders like that with a few thousandths neck tension.
What’s the diameter of the mandrel you used?
 
0.262” Same mandrel I used to prep/load the first box of brass without issue. I thought the same, the mandrel will get everything opened up just right. But that raised internal rim you can see in the second photo springs back more than the rest of the neck. There was definitely more resistance toward the bottom of the neck when running the mandrel through this brass. Maybe I will anneal and resize to see what I end up with.
 
I would just send the brass back, sounds like a bad batch dude. No point in chancing blowing something up.
 
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Neck outside diameter is a pretty consistent 0.2925 until you get about 80% of the way down the neck, where it increases in dia by .0005 to .001”. Then below that it decreases to 0.2925” again. Neck thickness is a very consistent .0145”. I can’t measure the thickness at that raised internal rim with my thickness caliper as the outer stem hits the shoulder, but, I can see it Is raised there.

Then you don’t have a doughnut. If you did the dia on the bottom of the neck would increase substantially.
 
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I would just send the brass back, sounds like a bad batch dude. No point in chancing blowing something up.
That first box was so perfect. It just seems more likely that they know what they are doing compared to me not knowing the best way to resolve this. Probably not a bad idea to mail it in to get their guidance.

Thanks to all for your input.
 
Then you don’t have a doughnut. If you did the dia on the bottom of the neck would increase substantially.
Reread the last sentence, that sentence explains things.

@SmokyJoe, it looks like your your chamfer/deburr is good, no burrs there to hang things up. Do you have pin gages? That’s a really good way of telling if you have issues with donuts or sort out neck tension. Me personally, I believe you on your donut prognosis, I really think most if not all cartridge cases have them it just depends on you dies, settings of your dies on how bad they can get. The best way I found was to neck turn with the same or about the same degree cutter to the shoulder angle degree and cut just slightly into the neck/shoulder junction.
 
Neck outside diameter is a pretty consistent 0.2925 until you get about 80% of the way down the neck, where it increases in dia by .0005 to .001”. Then below that it decreases to 0.2925” again. Neck thickness is a very consistent .0145”. I can’t measure the thickness at that raised internal rim with my thickness caliper as the outer stem hits the shoulder, but, I can see it Is raised there.

No it doesn’t
It says he couldn’t measure it, just because there’s no measurement don’t mean there is or isn’t a donut there.....so just telling him he doesn’t have one because he couldn’t measure that spot doesn’t help the OP out.
 
Remember, this is new brass. I’ve not sized it. All I’ve done is run a 0.262 mandrel through it, noting that the mandrel was hard to push through the bottom of the neck. Then when I tried to seat a bullet, it was difficult to fully seat, crushing the case when pushed past the bottom of the neck. I don’t know if it’s a donut or a bagel or just an unfortunate obstruction. I do know it’s not ‘normal’ and will be sending the brass back to ADG for their review. I do appreciate your thoughts on this, and will let you know what ADG has to say.
 
That sucks. Donut looks clear. I've inside neck reamed to clean up galled and donut cases.

Question is, is your reloading causing the donut?

If I had to guess its under anealed and undersized bushing causing a donut that springs back. Hard to belive a donut alone would cause enough resistance to crush a case.

What Dies and bushings and mandrels are you using?

Case neck measurement with a bullet?
 
Remember, this is new brass. I’ve not sized it. All I’ve done is run a 0.262 mandrel through it, noting that the mandrel was hard to push through the bottom of the neck. Then when I tried to seat a bullet, it was difficult to fully seat, crushing the case when pushed past the bottom of the neck. I don’t know if it’s a donut or a bagel or just an unfortunate obstruction. I do know it’s not ‘normal’ and will be sending the brass back to ADG for their review. I do appreciate your thoughts on this, and will let you know what ADG has to say.

You don’t have a doughnut. What you describe is normal for new brass. Well not the crushing part but the feeling of the expander pushing through the neck.
 
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Remember, this is new brass. I’ve not sized it. All I’ve done is run a 0.262 mandrel through it, noting that the mandrel was hard to push through the bottom of the neck. Then when I tried to seat a bullet, it was difficult to fully seat, crushing the case when pushed past the bottom of the neck. I don’t know if it’s a donut or a bagel or just an unfortunate obstruction. I do know it’s not ‘normal’ and will be sending the brass back to ADG for their review. I do appreciate your thoughts on this, and will let you know what ADG has to say.

Once you ran it up a die it is no longer new.
 
Remember, this is new brass. I’ve not sized it. All I’ve done is run a 0.262 mandrel through it, noting that the mandrel was hard to push through the bottom of the neck. Then when I tried to seat a bullet, it was difficult to fully seat, crushing the case when pushed past the bottom of the neck. I don’t know if it’s a donut or a bagel or just an unfortunate obstruction. I do know it’s not ‘normal’ and will be sending the brass back to ADG for their review. I do appreciate your thoughts on this, and will let you know what ADG has to say.
Bud I feel your pain!!! I chased the donut deal down a very long rabbit hole with a fair amount of money spent and lots and lots of time involved researching! What changed a lot was talking to an F-class shooter and he stated that whatever your brass prep first off keep it going, be consistent with your process. Virgin brass gots different stuff done to it but not by much.
 
This is why my favorite FL die is basic Lee, lol.
 
Just read, new brass.

Not annealed?
ADG annealed it as new brass. This batch was what they call ‘Bright’ meaning they clean the annealing discoloration off before shipping.

Once you ran it up a die it is no longer new.
Right...by new I meant unfired.

It’s not been put through a sizing die by me. I’ve only run the mandrel through and trimmed/chamfered it. I’ve used this same process for plenty of ‘new’ brass and never run into this particular issue. Since I can clearly see a raised rim at the inside base of the neck, and since the case deforms when a normal diameter bullet is pushed through that raised rim, it seemed prudent to ask if anyone knew of a way to resolve this without having to use an inside reamer. Using an inside reamer seemed like a great way to spend on new tooling just to make an off-center mess. In any event, no big deal. The brass can be replaced if necessary. ADG makes great brass and should have some good insights/advice.
 
All? Really? Because I swear my new Hornady is not. And this brass definitely does not appear annealed.

It’s annealed. The annealing marks were polished off prior to packaging. Most commercial brass is polished before packing. Only the military insists on annealing marks being visible.
 
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ADG annealed it as new brass. This batch was what they call ‘Bright’ meaning they clean the annealing discoloration off before shipping.


Right...by new I meant unfired.

It’s not been put through a sizing die by me. I’ve only run the mandrel through and trimmed/chamfered it. I’ve used this same process for plenty of ‘new’ brass and never run into this particular issue. Since I can clearly see a raised rim at the inside base of the neck, and since the case deforms when a normal diameter bullet is pushed through that raised rim, it seemed prudent to ask if anyone knew of a way to resolve this without having to use an inside reamer. Using an inside reamer seemed like a great way to spend on new tooling just to make an off-center mess. In any event, no big deal. The brass can be replaced if necessary. ADG makes great brass and should have some good insights/advice.

How’bout using a larger mandrel??? I use an expanding mandrel rather than a turning mandrel. The former is .001” bigger than the latter.
 
How’bout using a larger mandrel??? I use an expanding mandrel rather than a turning mandrel. The former is .001” bigger than the latter.
That could work, and I do have an expander mandrel from back when I used to do some neck turning. The resultant may be that the majority of neck tension would be concentrated where the rim is. And what happens with that extra rim of brass at the base of the neck over several firings? The more I think it through, it seems that at $1.60 per case that obstruction should not be there. Do you know if they inside neck turn, or otherwise mitigate this kind of issue at the factory after forming?

Back when I did neck turning, one of the the goals was to do it before first firing, and to cut the neck/shoulder junction to prevent a donut from forming that would be pushed inside when sizing. Well, this is already there on unfired brass, so I can’t pre-empt it, and, I really want to avoid inside reaming.
 
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They don’t ream the inside.

I would expand, use a dry lube, seat the bullets and shoot. Then resize and see if the problem is there.
 
IMO, even if by some weird circumstance, that brass had a donut when it was shipped the expander mandrel you pushed thru there should have moved the donut to the outside. Unless you are passing it thru a sizing die (neck or FL) AFTER the expander mandrel the donut should stay on the outside of the case.
Using Imperial/Redding dry media inside the necks will help with bullet seating on new brass. It also greatly reduces chatter when mandrels or expander balls go thru the necks during reloading process. I have (rarely) had the same result of trashing brass seating bullets and it is most likely on virgin or SS tumbled brass where the inside of the necks are spotlessly clean. The dry media doesn't contaminate powder and does not need to be removed before bullet seating. In fact it may even lower your ES/SD due to the fact it will make neck tension more consistent.
As far as inside neck reaming that is a process used to fuck up brass to the point of having to throw it in the trash UNLESS you are a very experienced reloader, have a most thorough understanding of the process and have exactly the tools necessary to do the job.
 
IMO, even if by some weird circumstance, that brass had a donut when it was shipped the expander mandrel you pushed thru there should have moved the donut to the outside. Unless you are passing it thru a sizing die (neck or FL) AFTER the expander mandrel the donut should stay on the outside of the case.
You are right, the mandrel should push it out. The fact that it didn’t, after two passes with the mandrel, has me thinking that maybe the brass is too hard. No sizing die was used. Also, I always use dry lube. The bullets I was loading were coated with hBN and I dust the inside of the necks with hBN.
 
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Cut a piece lengthwise with a Dremel or hacksaw. Send pictures to adg and post here.
Eta, or have someone mill it in half
 
I ran a piece from the first box through the AMP annealer Aztec mode and got a code of 6819. This is once fired brass.
Ran a piece from the second box (unfired) through and got a code of 7989. Not sure what the delta signifies, especially since one is fired.

I will cut a few pieces to have a look at the internal profile. Also going to anneal a few then prep and try to load them.
 
A mandrel pushed through the neck one time will NOT necessarily push the doughnut out, multiple passes may be required.
I have personally had where using the same exact die, same batch of cases, one bunch was expanded with a mandrel pushed into the case
the second bunch expanded with the stock expander button pulled up through the neck.

The cases that a mandrel was used all had doughnuts the batch that the stock expander button was used had NO doughnuts, all checked with pin gauges.
 
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Uninstall your dies, then reinstall them, taking special care to follow directions.

at least one of them is adjusted currently so low that the neck end is visibly shorter than the case neck in the properly loaded cartridge. It's set up adjusted too low.

Greg
 
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Uninstall your dies, then reinstall them, taking special care to follow directions.

at least one of them is adjusted currently so low that the neck end is visibly shorter than the case neck in the properly loaded cartridge. It's set up adjusted too low.

Greg
I should have been more clear about the two cases shown. The one on the left is not fully seated. I stopped seating that one when resistance increased. Even though I stopped, the shoulder/case junction had started to bulge outward. You can see the slight curvature in the photo. Regarding the seating die, I can set an unloaded case in the Forster, cycle the handle all the way down, and the die does not interfere with or touch the case.
 
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The cases that a mandrel was used all had doughnuts the batch that the stock expander button was used had NO doughnuts, all checked with pin gauges.
Maybe the mandrel is scraping/shoving brass down the neck? Or changing case length enough to slightly compress the neck at the shoulder?
 
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OK, looking at the potential variables again, I am coming up with bullets that are 0.2645”; last batch was 0.264”, Mandrel is same size 0.262” Cutaway of the brass shows a very slightly constricted ring inside at the bottom of the neck. Maybe that all adds up to too much neck tension. Doing the math, it would be maybe .003+/- instead of .002, so should not be an issue. Pin gauges would be nice! Anyone sell a reduced set from .260 to .270?

As a test I annealed 5 pieces of the new brass, FL sized it, ran the mandrel through twice, lubed the neck with hBN, then attempted to seat the 0.2645” bullets. Too much tension. Found some 0.264” bullets, and was able to seat those with a bit more resistance than normal, but no case deformation.

I’ll send this photo to ADG and will report back with their conclusions. Probably just need to get a 0.263 mandrel, or use the expander ball as 918V and Whatsupdoc have suggested.
 
From pictures on phone I dont see a problem.
1. ID too small?
2.Bullet too big
3. Lube your bullets or necks
 
Amazon sells individual pin guages on the cheap. You can put together a set to cover the range your working in.

Hard to believe there is enough neck tension after the mandrel to crush the case. At this point I would be looking at a possible issue with the seating die.