donuts


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taliv
September 4, 2010, 10:21 PM
so... i'm experiencing something new reloading my 260 AI. For starters, I'm full-length resizing, but only resizing half the neck, and only putting a thou of tension on it.

When I seat a bullet, i feel two very distinct points of resistance. First when the bullet starts getting pushed into the neck, and then a second one, as if i'd resized the top and bottom of the neck but not the middle. weird.

i'm speculating donuts have formed and i'm having to push the bullet base past one, which is causing the resistance, which feels consistent on every case.

anyone ever encountered this before? What tools would you use to measure it? i don't really have any desire to buy or use an inside neck reamer. and i don't really want to section a case either.

fwiw, i put the bullet into the lands a bit. and i chrono'd 4 rnds yesterday at 3047, 3048, 3046, 3048. then shot 5 into an inch at 200 yrds (see my post in the indian summer long range match) so it doesn't appear to be causing any problems yet...

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jr_roosa
September 4, 2010, 10:48 PM
Is you seating die trying to crimp?

Run it without a bullet in and see if you get the resistance at the top of the seating stroke.

-J.

Sunray
September 4, 2010, 11:08 PM
"...donuts..." Bait for cops and bears. snicker.
"...I'm full-length resizing..." If you're FL resizing, you're not resizing just half the neck.
"...two very distinct points..." Case mouths chamfered and deburred?

taliv
September 4, 2010, 11:13 PM
roosa, hmm... i'll try that soon. i already loaded all my sized brass so i'll have to shoot one and try it. i am under max case length, but right around the trim length.

If you're FL resizing, you're not resizing just half the neck.

yeah, i am.

woods
September 5, 2010, 03:28 PM
I don't know if you have a do-nut or not but there is one sure way to tell: insert a bullet into a unsized case, if it stops and won't go further than the shoulder/neck junction, then you have a do-nut
http://img.photobucket.com/albums/v663/bwestfall/RELOADING/3D-308-doughnut.jpg
http://img.photobucket.com/albums/v663/bwestfall/RELOADING/3D-308-doughnut2.jpg

Do-nuts can happen on any case but if you have a chamber with a lot of clearance around the neck then the do-nut will not protrude enough to stop the bullet. In that case it would not have any bearing since if it does not hit the bullet before sizing then it will not hit the bullet after sizing. Since you have an AI chamber it is probably custom and a tight neck. Do you outside neck turn in order to get the neck thickness down for chambering?

There is another way to determine if you have a do-nut and that is with pin gauges
http://img.photobucket.com/albums/v663/bwestfall/RELOADING/DSCN1489.jpg
http://img.photobucket.com/albums/v663/bwestfall/RELOADING/DSCN1493.jpg

I develop do-nuts if I use Nosler 280AI brass, the bullet on the left is stopped at the shoulder/neck in an unsized case and the load on the right is a seated bullet in a loaded round
http://img.photobucket.com/albums/v663/bwestfall/RELOADING/DSCN0689.jpg

I use a Forster reamer to get rid of it
http://img.photobucket.com/albums/v663/bwestfall/CASE%20PREP/DSCN0716.jpg

but you have to set your brass up for an inside diameter of .003" after firing and ream on once fired cases.

taliv
September 5, 2010, 07:09 PM
Thanks! Yes it's a slightly tight .296 neck and I neck turned but really only cleaned it up. I didn't take much off

What if my cases are already fired three times?

Walkalong
September 5, 2010, 07:30 PM
They can still be neck turned again. For a Bench gun though, I would have tossed the batch and started over. You can also ream out the donuts. I assume this is for a target rifle, so I may be inclined to do the same.

Make sure your necks are a tight fit on the neck turning mandrel, and turn down the entire neck and into the shoulder a hair.

I used to inside neck ream, then outside neck turn to my desired thickness. Wilson reamer used in the Wilson trimmer, and a K&M neck turner.

taliv
September 5, 2010, 09:17 PM
thx, walkalong. Whatever is causing it didn't show up until after I'd shot the brass 2x and was loading #3. I shot #3 today in a 1000 yrd match. Necks are tight fit and i did turn into the shoulder just a hair. I don't think neck turning will help though. Neck reaming is what i'd need. or are you saying turning is what caused the donut?

taliv
September 5, 2010, 10:04 PM
woods, i tried seating a bullet in an unsized case and it slides back until exactly where the top of the boat tail hits the neck/shoulder junction.

so now the question is... how much worse will this get? i mean, i still shot a 1"ish group at 200 yrd friday and a 392-11x at 1000 today. that's plenty good enough for me, as long as it doesn't start causing inconsistencies that open up the groups.

Walkalong
September 5, 2010, 10:34 PM
Yes, neck turning and stopping short caused the donut. It moved forward as the case stretched. That is why you noticed it after the second firing. Ream it out and load them up. Be careful to ream them just right. Barely touch the inside of the neck and remove the donut.

I only have experience with donuts and 6 PPC in tight necked chambers where we sized the brass very, very, minimally. I would bump the shoulder .001 max, and have less than .001 clearance in the neck area. It may be impossible to avoid the donut when sizing more and having more case stretching going on. I dunno.

zoom6zoom
September 5, 2010, 10:35 PM
Darn, was looking forward to sugary goodness. DisaPOINTED!

woods
September 6, 2010, 12:42 AM
I don't know if it will get worse since I get rid of mine when it happens. Each rifle is an individual but it made a difference in my gun
http://img.photobucket.com/albums/v663/bwestfall/TARGETS/DSCN0798.jpg

Like Walkalong I've heard that turning into the shoulder can keep them from forming and that is typically the way I do it (338RUM case shown here)
http://img.photobucket.com/albums/v663/bwestfall/CASE%20PREP/DSCN0497.jpg

but it did not work with my Nosler 280AI brass. Oddly enough if I fire form Nosler 280 rem brass into 280AI then I don't get the do-nut. Since I have the Forster outside turner I turn my brass so that the neck thickness gives me .004" clearance on a loaded round

.294" neck on a 6.5 rem mag - loaded neck OD .290"
.313" neck on a 280AI - loaded neck OD .309"
.366" neck on a 338RUM - loaded neck OD .362"

and after firing and springback I get .003" over caliber ID which is what the Forster reamer is.

Since I have a reamer and can take care of it I don't have to find other solutions but I have often wondered if outside neck turning to give you a lot of clearance around the neck would preclude do-nut forming. IOW if you had for instance .006" clearance like a factory chamber, then even if the do-nut formed it may not bear on the bullet.

Would depend upon how much neck thickness is left when outside neck turning though. Don't want to go much under .012" and definitely not under .010".

fguffey
September 6, 2010, 07:22 AM
I start out to form cases, I formed 30/06 cases down to 22/6mm (243) Wildcat without pulling a neck expander back through the case because I create DONUTS, on this project the donut (restriction) inside the neck would require reaming (removing) before the case could have been used as a 6mm Remington, that is one form of donut.

A different donut??? is created when neck sizing, only the portion of the neck that is sized is reduced in diameter when neck sizing, the portion of the neck that is not sized remains unsized, not all bad, the unsized portion of the neck will center the front of the case in the neck of the chamber, but partial neck sizing does not create a donut, neck sizing reduces the diameter of the neck that is sized, and if an expander ball is used, the unsized portion of the neck will not contact the neck sizer expander ball.

Then there is the line of reloaders that are standing at the new product window, the ones that have to have every new tool that is introduced, it is possible to create the appearance of a donut when in fact it is a bulge created by jamming the neck by holding it inside and out and at the same time the case up is pushed up. or by forcing the jammed neck down onto the case body, this creates a bulge.

So it is possible to create a donut when firing a case, if brass stretches and or flows, at the neck, there are two radius at the case shoulder/neck juncture meaning brass that flows past that point has further to go on the outside than inside and for those that can get their minds abound it, the outside of the case is locked to the chamber so a guess would be the brass flows around the corner causing to to wad up, and the shoulder angle determines the likely hood of this happening.

You say the donut?? did not appear until you neck sized (with a colet die?).

I would suggest, if you are using the versatile full length sizer die remove the primer punch/neck expander assembly then size a few cases then examine for a donut (innie)then install the primer punch/expander ball assembly and size a few cases and check for a donut on the outside (outtie), if a donut appears on the outside of the neck at the shoulder/neck juncture after full length sizing the neck expander ball is pushing it out when it is pulled through (the restriction).

So, a do-nut can form inside the neck at the shoulder/neck juncture when forming a case, forward brass flow can create a do-nut inside the case at the shoulder/neck juncture, a do-nut looking ring can appear around the neck at the shoulder juncture when partial neck sizing, I examine cases for donuts inside the neck first, if the brass flow is smooth when it flows past the shoulder/neck juncture, a do-nut will not appear on the outside of the neck unless I am using one of those 'you gotta have' dies, and the neck sizer die does not create do-nuts.

F. Guffey

fguffey
September 6, 2010, 07:46 AM
Taliv,"so... I'm experiencing something new reloading my 260 AI. For starters, I'm full-length resizing, but only resizing half the neck, and only putting a thou of tension on it."

full length resizing but only resizing half the neck?

I was asked to make some dies that would do just that, nothing new, there was a very talented smith out west that did just that, for me with my versatile full length sizer die, it is either-or, not both, unless I am out of touch and or someone has taken a liberty and put full length sizing in a category that includes variable sizing, again, I can neck size or full length size, full length sizing is restoring a case to minimum length, anything less than that becomes partial neck sizing with case body support, even then there is a limit when the body of the case is sized and the shoulder starts to take on the appearance of an arch or radius, meaning the shoulder moves forward when the case body is sized (a little), to control this I limit the gap between the top of the shell holder and bottom of the die.

F. Guffey

taliv
September 6, 2010, 10:29 AM
walkalong/woods, hmm... like i said earlier i DID outside neck turn and take it into the shoulder, but maybe i didn't go far enough into the shoulder. i will try that on my next box which i'm planning to prep today.

this rifle has a
.296 neck
.264 bullet
.015 brass neck thickness on the lapua 243
.014 brass neck thickness after expanding to 6.5
.292 loaded neck which gives me .002 clearance on either side


fguffey, if you use bushing style sizing dies you have a great deal of control over how you change the neck. for instance, if you don't put a bushing in at all, you could full length size the shoulder/body w/o ever touching the neck. obviously, put whatever diameter bushing you want in to set the amount of tension you want on the neck.

you can take it a step further by how far you screw the thing in that holds the bushing in place. the instructions for most dies say you should back off an 1/8 or 1/4 turn to give the bushing some play to align itself. but if you back off a couple of turns, then you will only resize the neck minus a couple turns. this is easy to measure. try it.

i like to seat bullets well into the lands, but put minimum neck tension required to keep the bullet in place while it's in magazine etc. in the rifle in question here, my bushing is only .001" smaller than the loaded round, so i'm putting minimal tension on it, and even less since i'm resizing only half the neck.

Walkalong
September 6, 2010, 11:41 AM
See the donut in some of them? It was well below where I was sizing the neck and seating the bullet, so it was not removed.

http://www.thehighroad.org/attachment.php?attachmentid=89893&d=1230389230

fguffey
September 7, 2010, 09:25 AM
Dies are sold with as many options as there are when ordering coffee, caff, de-caff, half-caff, light, regular, mocha, black etc, Sunray, without a hint from the OP as to what sizer die is being used is correct. It is not possible to get a case into the do-nut on the outside configuration. I believe the do-nut at the shoulder/neck juncture is created by the die as in full length sizing the body and partially sizing the neck (as the OP says, removing the bushing eliminates sizing the neck) and that being the case the do-nut is part of the sizing process as in the die at the top of the shoulder is too large in diameter to size all of the shoulder, In my opinion the 'so' called donut is a (flawed) design or function of the die, and I believe it is a mistake to turn the outside of the neck, like no matter what, it will heal it self, I agree with Walkalone, dump the cases until the phenomena is better understood.

I have competition and gold medal seater dies from RCBS and Lyman universal seater dies, Weatherby seater dies and bullet seating tools I have made that do not require a die,

http://www.rcbs.com/downloads/instructions/Gold_Medal_Dies_Instructions.pdf

but not the sizer dies, I am not going to start over, I have all the sizer dies I will ever need.

If not now, when? It would be irresponsible for me to suggest and or recommend turning the outside of the neck to remove material that is created by a design, and I believe someone should find another term that would describe the unsized portion of the neck created by the gap between the bushing and shoulder portion if the die.

and if the shoulder is being set back .001, where did the unsized portion of the neck come from, then we have to figure does brass stretch or flow?

A friend called with a problem, seems he built a rifle, loaded up a few rounds and went to the range, he examined the sixth case after firing, no neck, he removed the bolt, there it was in the throat of the chamber, he then checked the first five cases he fired and no necks on any of them, he then said he was going to quit taking advise on the Internet, the friend is very talented and knowledgeable and a good resource for information, his methods and techniques work. My advise to him: It is like the doctor with limited time, he is told 'it hurts when I do this', his advise, 'then don't do that'.

F. Guffey

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