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Originally Posted by mathman
Originally Posted by ShadeTree
Originally Posted by TeeBone
I'm somewhat perplexed by the donut problem, for only have known this problem with tight neck chambers, usually where case necks weren't cut fully down to the shoulder. I have cases that were fired 40+ times and never an issue. But for these I don't drag an expander ball through the necks either.

If I've gotten them I was both unaware of it and it wasn't bad enough that it ever caused an issue with either accuracy or pressure. I get long case life generally through a lot of loadings in a lot of different cartridges and it never shows up. I also use an expander ball so it's not that, at least not with me.

The ONLY time I seen it ever so slightly was after numerous loadings like 5 or 6 in a 35 Whelen, and each time it was loaded with a short bullet intended for 35 Remington. The Whelen with its long neck makes the base of those short bullets out the neck pretty far even when seated as deep as possible. I eventually could feel a slight ring just behind where that base was sitting. As already stated as long as I don't seat below that slight ridge with a different bullet, I don't see it will be a problem.

Those Whelen cases were expanded up from 30-06. No clue if that has anything to do with it or it is solely because of loading short bullets out the neck.


It's a likely cause. When necking up you get what was shoulder material becoming the lower portion of the neck.


Does necking up in steps make a difference? Or none? I use the Hornady expanders when necking up since they are tapered and make life easier. I made sure I had plenty of lube on the inside of the necks and necked up to .358 in 1 step. It went well, didn't lose a case.

I necked up a 6mm case to fire form in a 257 Ackley because I have plenty of 6mm cases so I figured that would be a good source for me. I went bigger than .257 initially to create a false shoulder. That worked out just peachy as far as fireforming but I haven't reloaded that case anymore.

If donuts are gonna be a problem from doing that I might have to get a neck turner and learn how to use it. Crap. My reloading room is starting to become disorganized so as it is.


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Originally Posted by Son_of_the_Gael
Seems to most commonly occur when part of the shoulder becomes part of the neck. For instance when a case is necked up to a larger caliber (perhaps 7mm-08 from .243) or if a case of formed into a shorter one (e.g. making .308 from .30-06). It doesn't always happen and I am sure there are other circumstances in which it may occur .

I gather the best fix is to run a mandrel or expander into the neck to push the donut to the outside and then turn the neck to remove the excess
I also prefer to turn the excess off the outside. It makes the case necks a uniform thickness.

If the case is thicker on one side than the other, a reamer will follow the hole and the neck will still be thicker on one side.

I can also keep the case and neck straight when turning but I don't have a lathe to keep a reamer straight.

As always, your mileage may vary.


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I get donuts with Lapua brass in my NULA 22-250, it has a tight chamber. American brass works great and I usually just use Winchester.


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Originally Posted by LBP
I get donuts with Lapua brass in my NULA 22-250, it has a tight chamber. American brass works great and I usually just use Winchester.

That sucks. You should try some Sig brass. See how it does. Although, I thought this was a thread about sticks quadruple chins AKA "neck donuts"..


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Necking up 243 brass to 260 educated me on donuts. Outside neck turning just uniforms the outside of the neck and doesn't effect the donut which is formed on the inside. When you seat the bullet the material on the inside causes the neck to expand possibly creating clearance issues, maybe squeezing the bullet if the rifle has a reasonably tight neck. This can cause high pressures but no matter what it makes for uneven neck tension. I did get away with using 243 brass some brands were OK. I ended up using 7-08 (best) and 308 brass which some brands needed the necks turned due to general thickness. I found some Nosler brass at a gunshow and bought 200 cases, though many say it is crappy brass this lot turned out to be the best I came up with for my 260.


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How do you determine if you have a donut? Visual? Measuring or feeling with some kind of gauge? This is all new to me, so please excuse my ignorance.

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Originally Posted by rickt300
Necking up 243 brass to 260 educated me on donuts. Outside neck turning just uniforms the outside of the neck and doesn't effect the donut which is formed on the inside. When you seat the bullet the material on the inside causes the neck to expand possibly creating clearance issues, maybe squeezing the bullet if the rifle has a reasonably tight neck. This can cause high pressures but no matter what it makes for uneven neck tension. I did get away with using 243 brass some brands were OK. I ended up using 7-08 (best) and 308 brass which some brands needed the necks turned due to general thickness. I found some Nosler brass at a gunshow and bought 200 cases, though many say it is crappy brass this lot turned out to be the best I came up with for my 260.

Not so.

Before turning the neck, I push the neck over an expansion mandrel. This pushes the donut to the outside, and it sizes the hole in the neck to be a close slip fit on the mandrel in the turning tool.

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Originally Posted by Jeffrey
How do you determine if you have a donut? Visual? Measuring or feeling with some kind of gauge? This is all new to me, so please excuse my ignorance.

Fired case, slip a bullet in down to the neck/shoulder junction. If the bullet stops or meets resistance before that you gots a donut.



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Originally Posted by Jeffrey
How do you determine if you have a donut? Visual? Measuring or feeling with some kind of gauge? This is all new to me, so please excuse my ignorance.

I should think pin gauges after FL sizing would be the best way.

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Originally Posted by LBP
I get donuts with Lapua brass in my NULA 22-250, it has a tight chamber. American brass works great and I usually just use Winchester.

Lapua 22-250 brass is kind of a unique problem, it exceeds SAAMI spec's !!!!!!!

About 20 years ago I had my own 22-250AI reamer made, it was based off of Norma and Federal brass. Winchester and Remington were the smallest to SAAMI spec so I never had an issue with any of it until Lapua came out with 22-250 brass about 10 years ago.
I had an issue the first time I used it and found by measuring that it was bigger in every dimension than every other brand on the market. It works fine in most sloppy factory chambers but not in a tight chamber.

Lapua has suspended production of 22-250 brass, they might have realized they had an issue

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Originally Posted by bsa1917hunter
Originally Posted by LBP
I get donuts with Lapua brass in my NULA 22-250, it has a tight chamber. American brass works great and I usually just use Winchester.

That sucks. You should try some Sig brass. See how it does. Although, I thought this was a thread about sticks quadruple chins AKA "neck donuts"..

I might give it a try, the brass that is.

Originally Posted by boatanchor
Originally Posted by LBP
I get donuts with Lapua brass in my NULA 22-250, it has a tight chamber. American brass works great and I usually just use Winchester.

Lapua 22-250 brass is kind of a unique problem, it exceeds SAAMI spec's !!!!!!!

About 20 years ago I had my own 22-250AI reamer made, it was based off of Norma and Federal brass. Winchester and Remington were the smallest to SAAMI spec so I never had an issue with any of it until Lapua came out with 22-250 brass about 10 years ago.
I had an issue the first time I used it and found by measuring that it was bigger in every dimension than every other brand on the market. It works fine in most sloppy factory chambers but not in a tight chamber.

Lapua has suspended production of 22-250 brass, they might have realized they had an issue

That’s exactly my experience.


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I tried a small hole gauge ,it's very much a feel thing. As such, a clean inside of the neck would be necessary . Good idea, using a pin gauge. I'll see if I have the correct size pin.


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Originally Posted by mathman
Originally Posted by rickt300
Necking up 243 brass to 260 educated me on donuts. Outside neck turning just uniforms the outside of the neck and doesn't effect the donut which is formed on the inside. When you seat the bullet the material on the inside causes the neck to expand possibly creating clearance issues, maybe squeezing the bullet if the rifle has a reasonably tight neck. This can cause high pressures but no matter what it makes for uneven neck tension. I did get away with using 243 brass some brands were OK. I ended up using 7-08 (best) and 308 brass which some brands needed the necks turned due to general thickness. I found some Nosler brass at a gunshow and bought 200 cases, though many say it is crappy brass this lot turned out to be the best I came up with for my 260.

Not so.

Before turning the neck, I push the neck over an expansion mandrel. This pushes the donut to the outside, and it sizes the hole in the neck to be a close slip fit on the mandrel in the turning tool.

There will still be some spring back. To me the best way to go is use brass from a cartridge that starts out with a larger diameter and neck down. Or seat the bullet where the base (full diameter) is above the thicker metal. At least this is what I did to suit what is probably the most accurate barrel I have owned.


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Mathman is correct. The mandrel pushes it to the outside but some folks forget to turn slightly into the shoulder where the donut material resides. First firing brass flow will fill in the slight gap and 99% of the time donuts don’t reappear.



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Originally Posted by Swifty52
Mathman is correct. The mandrel pushes it to the outside but some folks forget to turn slightly into the shoulder where the donut material resides. First firing brass flow will fill in the slight gap and 99% of the time donuts don’t reappear.

So you are saying that you feel the inside of the neck is parallel after being outside turned on a mandrel? If the case had a pronounced "donut" and the mandrel pushes it out is the mandrel supporting the rest of the neck evenly? In my humble estimation best results happen with outside neck turning when the neck ID is straight and without a lump on the inside. But good luck with all that.


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The neck is sized small enough that the expansion mandrel is in interference fit contact with the neck even before it gets down to the donut. It's not just pushing out the donut.

As to good luck, the cases I process by this method subsequently size dead straight. Something must be going right.

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Don’t think he will read it but good article on neck turning. Even covers the dreaded donut.

https://coyotestuff.com/case-neck-turning-step-by-step/



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Originally Posted by mathman
The neck is sized small enough that the expansion mandrel is in interference fit contact with the neck even before it gets down to the donut. It's not just pushing out the donut.

As to good luck, the cases I process by this method subsequently size dead straight. Something must be going right.

So when the donut hits the mandrel and pushed off of it doesn't this move metal in front of it off the mandrel a bit? This would seem like it would cause the case neck ID to vary at that point compared to the rest of the case neck. When I turned the necks for my match ammo I liked to get the outside neck clearance pretty close to .001 or .0015. Now suppose I am turning necks as you suggest but adding that variable? Now if you are just building brass for a hunting rifle sure, clearance is all that matters.


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I have not observed that problem occurring.

When you say .001" clearance are you talking loaded neck to chamber? When I was studying up on neck turning I found a lot of serious BR guys who would say that's too tight.

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Originally Posted by Swifty52
Don’t think he will read it but good article on neck turning. Even covers the dreaded donut.

https://coyotestuff.com/case-neck-turning-step-by-step/

Excellent link. That said the donuts I am considering are those caused by necking up say 243 cases to make 260 Remington cases. Not formed by not turning the necks far enough back. The problem being the thicker material that was shoulder and is now part of the neck. This can reduce inside diameter as much as .004. I think it is better to avoid that issue by necking down from 7-08 or 308 and then outside turning the necks to the diameter that suits the rifles chamber.


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