Dreaded Doughnut

[243jimb]

I handload for my .204 Ruger with a slightly tight neck (around .229") and I noticed that the acccuracy began to deteriorate after the cases had been fired a couple of times. Then I discovered that there was a doughnut inside the neck and a bullet would not slide all the way into a fired case.
I realise that this has to be removed and I have seen Forster's inside neck reamer and also RCBS's case trimmer pilot/reamer. So here is my question; how should the doughnut be removed? What I am considering is reaming a fired case with the Forster then resizing and neck turning the outside then using the RCBS pilot/reamer to keep it that way.
If it is of interest the loading info is as follows;
Nosler case, 27.7 grains H4895, Berger 40 grain bullet and a Federal GM primer. The Redding Type S dies have a .224" bushing (giving .003" tension) set to size around 2/3 to 3/4 of the neck. It is set to bump the shoulder .001"-.002".
Any input from those who have successfully fixed this problem would be appreciated.
Thanks, Jim.

 

[Nomad47]

Myself, fdshuster, and a couple others use a small rattail file to remove the donut - but it is time consuming. And is easier done on larger caliber cases that your 20 caliber cases.
My current solution is to load the bullets so they don't contact the donut. On two of my rifles that meant reaming the throat a little longer so I could seat the bullet longer.

 

[Bobr]

Had the dreaded donut on my 260 brass after 6 firings, this is what worked for me. This was Lapua brass that had been neck turned to .0125 before it was ever used. After having DJ ultrasonic clean and anneal I used the K&M 6.5 expander mandrel which pushed the donut to the outside. K&M trimmer was already set to the .0125 and by recutting the neck, only the donut area was cut off. Really amazing how much brass was taken off the last 1/4 of the cut. After neck sizing, the bullets have so far seated with even pressue all the way after 3 more firings. Hopes this helps
Bob

 

[Joe Maisto]

BobR1

Interesting how you got rid of your doughnuts. A lot of us in short range BR have them. Most have never found it to be a problem, as we don't seat that deep with a 6PPC. I bought an inside neck reamer but it was money wasted because I don't have a lathe, therefore it was impossible to get it exactly centered. So now I just shoot them with the donut. Does not seem to affect anything for accuracy, ( altho one would think it might)

Joe

 

[timeout]

I had a K&M neck turner once upon a time. I was thinking that the K&M mandrel had a cutter built into the leading end that cut out the donut. Also, if you already have an LE Wilson case trimmer, they make inside reamers for them. They have standard sizes or will custom make any size you want. I'm guessing that using the Wilson method surely would center the reamer?

 

[Bobr]

Only the carbide mandrel for the K&M turner has the cutter, the steel mandrel is straight. Tried the carbide once and it felt like I was taking a chain saw to this precision piece of brass I had labored to create.

 

[BoydAllen]

The doughnut should only be a problem if the shanks of your bullets fall within them. How do you set your FL die? The reason that I ask is that excessive shoulder bump causes doughnuts to appear in fewer sizings.

 

[Joe Maisto]

Boyd;

I've thought about this donut thing for a bunch of years. My thinking was...
Seemingly...it would constrict ( however little) the burn rate, therefore impeding accuracy . After more thought, I concluded that if in fact that occured, it would only be noticeable at long range, so I quit worrying about it.
On the OTHER hand, If you fire one with a donut, and the next subsequent round fired doesn't have one, Wouldn't you think it might make a differance...........shooting 'group at 200 ?

Joe

 

[BoydAllen]

For a top of the line, well tuned, well shot, benchrest rifle, I think that you may be able to see things that get lost in the noise in other situations (like .204 varmint rifles). If they (doughnuts where the bullets don't reach them) made a difference, do you think that it would show up on a chronograph?

.204 story: A friend found his best .204 Ruger performance with 32 gr. bullets and a warm load of TAC, but the ES would run as high as 50 FPS. Since he builds his own rifles (including the .204), he decided to run the reamer in to the right length for a .223 case, (.080 short, I think) and cut off his dies to match. It shoots bugholes with the same components, the load is compressed, and ESs are high single digit. Just a little something to think about. BTW, it was the same rifle and barrel, a Lilja.

 

[Nomad47]

Boyd, you lost me. If he ran the reamer in, I would think that would lengthen the chamber. Then he cut off his dies??? Which would make them shorter?? Did he start by setting back the barrel a few threads?

 

[BoydAllen]

Yes. I should have mentioned that.

 

[dabibbee]

243jimb

I had the same issue with my 243 Remington cases after 2 firings. I had to not bump the shoulder as hard On the F/L sizing die and I used a thinner lock washer on my Redding competition seating die.
I think the shoulder bump was causing the transition to the neck to be too sharp and the combination of the competition seating die's.shoulder was pushing down on the neck of the case. Not sure if this was the case but it solved my problem. Best of luck.

 

[300meter]

So, what is the cause of the donut? Can you prevent it? Never had this issue.

 

[dabibbee]

300meter

Boyd and I believe it starts with excessive shoulder bump. However I believe
that excessive neck tension or in my case it was the competition seating die which needed to be lower in the press so that the micrometer would ride higher.
At any rate the seating die was pushing down on the end of the neck just a few thousands causing the donut. It fixed my problem to raise up bullet seater.

 

[BoydAllen]

In some cases there is a marked difference in the thickness of the brass in the shoulder, and the neck. When a case is FL sized there are two things that tend to move the top of the shoulder into the bottom of the neck, reduction of the diameter of the body of the case, and the shoulder being pushed back, bumped. Because the neck portion of the die won't allow the thicker brass to stick out any farther than that which is adjacent to it farther up the neck, it protrudes to the inside. A further contributing factor to tightness at the neck shoulder junction is the reinforcing effect of the shoulder that causes the bottom of the neck to be harder to expand, and to have more spring back after it is, even if excessive thickness is not present. IMO the best way to approach this problem is to have a long enough chamber throat so that bullet shanks do not fall in the area where doughnuts are likely to be formed.

I have a question for the long bullet shooters. Have you proven by any sort of test (however informal) that doughnuts matter when bullets are not seated into them? The reason that I ask, is that I have them in some of my 6PPC cases, and I cannot find any reason to remove them. They don't seem to affect accuracy. For that reason, I simply ignore them.

 

[Nomad47]

In addition to Boyd's comments. Two things that can cause donuts to form.
1. Necking up (6.5-284 to 284, for example), as thicker shoulder material becomes neck material.
2. After several firings and a couple trimmings, brass flow has caused shoulder material to flow into the neck.

 

[BoydAllen]

Yep, I let that one get by me. As a matter of fact, it is a major reason for doughnuts in 6PPCs. Good catch.