Removing Case Neck Donuts?

Verminator2

New member
Hey all,

I've been working out a load for a new .260 Remington and have been getting somewhat erratic accuracy. A lot of loads couldn't be proven more than once and quite a few flyers. I think the problem is partially having a picky rifle, but while I was fiddling around with some brass I noticed that a bullet won't freely slide through the case neck. Some hang up just a little, while others take quite a bit of force to make it past that neck/shoulder junction. From what I can tell, this is a sign that donuts are forming inside the case neck. Unfortunately, I don't have any pin gauges or concentricity gauges to play with and check this.

The brass is Lapua .260 on its 5th firing. After firing, I run the cases through a Lee Collet neck sizer, and then again through a Redding competition body sizer to bump the shoulders back about 1-2 thou's.

I've tried looking online for information on how to prevent and remove the donut, but I'm having a hard time making sense of it all. I don't have any neck turning tools either. My questions would be is there a particular reason why donuts are forming even though I'm not necking up/down brass? What do I need to buy to remove the current donuts? What should I do to prevent donuts from forming?

Any advice is appreciated! Thanks,

Ben
 
Originally Posted By: Verminator2Hey all,

I've been working out a load for a new .260 Remington and have been getting somewhat erratic accuracy. A lot of loads couldn't be proven more than once and quite a few flyers. I think the problem is partially having a picky rifle, but while I was fiddling around with some brass I noticed that a bullet won't freely slide through the case neck. Some hang up just a little, while others take quite a bit of force to make it past that neck/shoulder junction. From what I can tell, this is a sign that donuts are forming inside the case neck. Unfortunately, I don't have any pin gauges or concentricity gauges to play with and check this.

The brass is Lapua .260 on its 5th firing. After firing, I run the cases through a Lee Collet neck sizer, and then again through a Redding competition body sizer to bump the shoulders back about 1-2 thou's.

I've tried looking online for information on how to prevent and remove the donut, but I'm having a hard time making sense of it all. I don't have any neck turning tools either. My questions would be is there a particular reason why donuts are forming even though I'm not necking up/down brass? What do I need to buy to remove the current donuts? What should I do to prevent donuts from forming?

Any advice is appreciated! Thanks,

Ben

Donuts come from neck turning - they are a small ring a few thou thick, inside of the neck, just under where the shoulder meets the neck.

If you haven't neck turned the cases, then you do not/cannot, have donuts.

 
Thanks Cat, I was hoping you'd join in. Any ideas why some are harder to slip through than others once the bullet gets to the neck/shoulder junction? I wouldn't even worry about it, but my throat is so short that I can't seat above that tight spot. I was looking for something to blame the fliers on besides my shooting
lol.gif
 
Originally Posted By: Verminator2

The brass is Lapua .260 on its 5th firing. After firing, I run the cases through a Lee Collet neck sizer, and then again through a Redding competition body sizer to bump the shoulders back about 1-2 thou's.



In my opinion you might as well be using a type S FL sizer die if your using both a neck die and then a separate body die.

I would anneal the brass and FL size it with something with an expander to get a consistent sized neck to start. After that I would start using a type S neck die with the proper size bushing, pitch the Lee collet die in the trash and only use the body die when needed.
 
Anneal that brass. Things will go to normal.

as a side note. I would think about a mandrel die from either Lyman or Sinclair. Never pull a a sizing button through a case neck. The mandrel is much more consistent and much easier on the neck.
 
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Whole neck, about .004 tension.

Furhunter, the reason I am using two separate dies is I've heard from many people who did runout tests on brass that the Collet sizing die produces very little runout. I also bought into the theory that if your necks aren't concentric outside the bushing will favor the 'thicker' side and can cause runout issues. Of course, I have no way to verify that or test it myself. The body die I was using because I liked the idea that all of the cases are the same dimension, and very close to my chamber if I'm only bumping .001. Feel free to correct me if I'm doing something stupid!
 
Originally Posted By: Verminator2Whole neck, about .004 tension.

Furhunter, the reason I am using two separate dies is I've heard from many people who did runout tests on brass that the Collet sizing die produces very little runout. I also bought into the theory that if your necks aren't concentric outside the bushing will favor the 'thicker' side and can cause runout issues. Of course, I have no way to verify that or test it myself. The body die I was using because I liked the idea that all of the cases are the same dimension, and very close to my chamber if I'm only bumping .001. Feel free to correct me if I'm doing something stupid!

Is the separate body die operation screwing up what the collet die does?

Your brass gets fire formed to your chamber, then you size it back down with a body die. You might as well be using a FL sizer die.

.004 is a bit tight for neck tension. I try to keep mine about .002 or so.

Lapua brass is pretty consistent about neck thickness. I wouldn't worry too much about that right now, that's pepper you can pick out with a metal beak later.

Wouldnt be the first time I heard of a Lee collet die screwing things up.

Things just don't seem right so maybe its time to try something else. Your brass is 5x fired and probably needing annealed, neck tension is a bit tight and you may be over sizing your brass with a body die. I would step back and see what keeping it simple would do for ya.
 
Forster makes a great bushing neck shoulder bump die. Coupled with Lapua brass, all in one solution with anneal. Real simple.
 
Thanks for the advice guys! I'll try annealing and see if that fixes the problem. I'll also investigate changing my setup, I may have bit off something rotten and too much of it.

On a different note, I did end up with a load today that is consistently .5-.6 MOA at 400 yards. My frustration is that the rifle seems to shoot everything I put in it about MOA, but it really takes some tweaking to get it down to .5 MOA. Like 200 rounds of tweaking. And this is a new Benchmark barrel. Maybe you're right Furhunter, and the dies are the root of my problem.
 
Originally Posted By: Verminator2Thanks Cat, I was hoping you'd join in. Any ideas why some are harder to slip through than others once the bullet gets to the neck/shoulder junction? I wouldn't even worry about it, but my throat is so short that I can't seat above that tight spot. I was looking for something to blame the fliers on besides my shooting
lol.gif


It's your shooting
tt2.gif


I think your procedures are fercockta.

First, why are you "bumping" with a body die - a body die is a standard FL die without a neck section - that is oversizing.

Guys read garbage on benchrest sites about FL sizing and shoulder bumping and figgure it must be good, Right?

It ain't.

First, why are you FL sizing? Do you have a receiver stretch problem? Can you chamber a fired case without problems?... if you don't have a problem chambering a fired case, then put the body die away. Take it out ONLY when you have a case that chambers with more resistance than you are willing to put up with. Tight cases are a good thing.

BR shooters Full Length size (with special dies, NOT body dies) for reasons not related to best accuracy. Short range bench shooters wait until the wind is calm and then shoot as fast as they can... maybe the whole group in 10 seconds - so it is important that the bolt close with "0" resistance so the BR rifle does not move off line when reloading. Short range bench (for aggs) is is not the intense, precision, deliberate shooting (for group size) of years ago.

Second, park that Lee collet die in the local trash can.

If you want the absolute least neck run-out and concentricity, then get the Redding "Competition Bushing Neck Sizing Die" (NOT the Bushing "S" die).

You will get less than 0.001" run-out, even with plain ol' factory brass - they are a little expensive, but probable about they same as all the junk you bought.

In summary, you should not be "bumping" the shoulder... unless you are having to much resistance in closing the bolt on reloaded cases.

And you MUST start annealing your cases.

 
Originally Posted By: Verminator2How often do you anneal the cases? I'll research that. Thanks for setting me straight.

Depends on some variables - but typically 3 to 5 firings.
 
I got rid of donuts in a 30BR by sizing after firing and then running the 30BR tapered expander through the necks again. This brought the donut effect to the outside of the neck. Then I trimmed it off with my neck turning stuff. I cut just the excess brass pushed to the outside, at the joint where the neck meets the body. I had already turned my necks to the thickness I wanted. Don't see why it wouldn't work with any cartridge.

Tom
 
Originally Posted By: Furhunter

.004 is a bit tight for neck tension. I try to keep mine about .002 or so.



A question I have always wanted an answer to.

How do you measure tension (which is a force) in thousandths of an inch (which is a linear measurement)??

Regardless of what measurement your bushing says, the "tension" is determined by the amount of brass hardness, and the amount of neck spring back, and how much of the neck you sized.

If you size 1/2 of the neck with a -0.008" bushing, is it the same as sizing the whole neck with an -0.004" bushing (assuming the bullet contacts the whole neck).

I think you can only measure neck tension with a gauged arbor press and actually measure the seating force.

Stating that there is 0.004" of neck tension is meaningless, so you cannot say that 0.004" is too little or too much... of what??

Bullets seated in annealed necks will seat softer with a -0.004" bushing, then bullets will seat in necks that are not annealed with a 0.002" bushing.

We go to extremes to quantify everything, even that which is not quantifiable.

Give it some thought...

... lemme know what you think??

 
Originally Posted By: CatShooterOriginally Posted By: Furhunter

.004 is a bit tight for neck tension. I try to keep mine about .002 or so.



A question I have always wanted an answer to.

How do you measure tension (which is a force) in thousandths of an inch (which is a linear measurement)??

Regardless of what measurement your bushing says, the "tension" is determined by the amount of brass hardness, and the amount of neck spring back, and how much of the neck you sized.

If you size 1/2 of the neck with a -0.008" bushing, is it the same as sizing the whole neck with an -0.004" bushing (assuming the bullet contacts the whole neck).

I think you can only measure neck tension with a gauged arbor press and actually measure the seating force.

Stating that there is 0.004" of neck tension is meaningless, so you cannot say that 0.004" is too little or too much... of what??

Bullets seated in annealed necks will seat softer with a -0.004" bushing, then bullets will seat in necks that are not annealed with a 0.002" bushing.

We go to extremes to quantify everything, even that which is not quantifiable.

Give it some thought...

... lemme know what you think??



Cat.
Who's to say with annealed brass that once the bullet is seated its not all the same anyways? I agree with everything you said above, my only point to the OP was that .004 was a bit outside the norm of what most generally try to achieve.
 
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