Best Way to remove the dreaded donut?

[chomondely3]

6br- Lapua brass, no turn neck
Neck wall: .013
After firing: .271 OD

After sizing: .267 OD
.2412 ID at mouth
.2395 ID base of the neck
I am using a Brown &Sharpe small hole gauge set to measure the ID. I can feel the donut at the the base of the neck when I am seating a bullet.


What is the best tool to cut out the donut?

I have a K&M neck tool to turn brass for other calibers so I could use their cutting pilot.
Other options?

I know that I need to anneal this brass, but DJ is not taking orders the last time I checked. DJ is a great resource and I hope that he gets back into the annealing business soon.

Thanks for your help,
Chomondely

 

[RegionRat]

Reamers are sold for cutting the ID of necks. That said, I have had mine since I was very young and have never used them. I would consider that a last resort and I have always found alternatives.

You mentioned you were not able to anneal, but maybe tell us a little more about the history and sizing process of your brass. Maybe we can suggest an alternate approach to prevent or even cure the donut.
Are you planning to add annealing to your toolbox?
Do you use bushing dies?
Do you use mandrels?

 

[AlNyhus]

The cases should be fired and unsized before addressing a donut. Once the ID of the necks and donuts are measured exactly, then you can deal with it.

There's more to this than meets the eye.

Good shootin' - Al

 

[chomondely3]

Many times fired. DJ has annealed them in the past. Probably fired 7 to 10 times since DJ last annealed the cases. Will add an annealing device to the tool box if DJ not back in the business.
Redding body die if needed. Very rarely do I need to to use the body die. I usually neck size with Forster neck die, .266 bushing. .269 after loading.
In the recent past, I noticed inconsistent seating force, especially with a Berger 80 gr flat base. The 90 gr Berger feels like it sometimes touches the donut.
Once I did enough measurements to confirm that there was a difference in the ID of the neck between the end of the neck and the base of the neck, I did the following:

neck sized the brass with .266 bushing
used a K&M expander mandrel .2435
donut still present after running the mandrel into the brass
trimmed to 1.509
neck sized to the diminsions in the OP. Still have the donut.
Decided to seek help from the forum
Hope this additional info helps.
Thanks

 

[RegionRat]

I will give you a pointer by way of asking a question...
If you poked a 0.2435" mandrel into that neck, and it only came up to 0.2395", why didn't you try a larger mandrel till you got it up above 0.243"?

You can always bring it back down for say the upper 80% of the neck with a neck bushing, but it is worth a try with the mandrel to open it up at the neck-shoulder junction till you are happy with it.

The down side is you have to learn to do this without over working the brass since you don't anneal, and you may find you will need to trial fit the cases to make sure your shoulder-neck radius still clears. You would then slightly bump size till you can close the bolt. YMMV

ETA: the more you cycle the brass without annealing, the more noticeable the difference will be in the neck with respect to the mouth which is unsupported versus the shoulder junction which becomes increasingly stiffer. In stress-strain terms, the mouth is free and unsupported but the bottom of the neck has a boundary value that is rigidly connected to the shoulder. For some distance away from that shoulder, there is a difference in the effect of the mandrel or bushing when the brass is significantly work hardened.

 

[jackieschmidt]

Not what you want to hear, but the best way to deal with the “dreaded do-nut“ is to use a reamer with the proper free bore so the shank of the bullet does not encounter it.

or, another option is use a UniThroater. That is kinda what it was invented for.

 

[AlNyhus]

To clarify....deal with the donuts with the cases/necks fired but unsized. -Al

 

[mikecr]

Is your bushing sizing the donut area?

 

[Webster]

6br- Lapua brass, no turn neck
Neck wall: .013
After firing: .271 OD

After sizing: .267 OD
.2412 ID at mouth
.2395 ID base of the neck
I am using a Brown &Sharpe small hole gauge set to measure the ID. I can feel the donut at the the base of the neck when I am seating a bullet.


What is the best tool to cut out the donut?

I have a K&M neck tool to turn brass for other calibers so I could use their cutting pilot.
Other options?

I know that I need to anneal this brass, but DJ is not taking orders the last time I checked. DJ is a great resource and I hope that he gets back into the annealing business soon.

Thanks for your help,
Chomondely

If the bullet doesn't seat deep enough to go against or past the donut do you have to remove the donut? I shoot 55-68 gr bullets in my 6BR. I split a neck with a Dremel tool to use for determining touch. You can see the bullet thru the cut all the way to the shoulder. I am only half way down the neck at touch with a 60 gr bullet. 55 Nosler gr bullets are only about 0.040" inside the neck. Been shooting an accurate rifle for Varmints since 1970, never removed a donut. Never checked touch with anything over 70 gr.

 

[Ccrider]

Why can’t you push it to the outside and then re-turn the neck?

 

[LC Tikka]

Ream the ID with the case neck inside a bushing, then the neck is round and can't flex away while cutting out the bulge.

 

[SKWERLZ]

Not what you want to hear, but the best way to deal with the “dreaded do-nut“ is to use a reamer with the proper free bore so the shank of the bullet does not encounter it.

or, another option is use a UniThroater. That is kinda what it was invented for.

Really this is an excellent approach

 

[snoopy001]

Really this is an excellent approach

The best approach to all of those problems for me was final decision to order
the IDOD Neck Turning machine from Bryan Blake .Count down is running,
i hope to receive them in 1 month then reloading will take a new dimension.

 

[Catfur]

Wilson makes a relatively inexpensive torture devi... er, inside reamer to cut out the donut in your brass.

It is effective, however, that way lies pain.

 

[boltfluter]

Or you can size the case in a full length die, install die in a lathe, case and all and ream the neck. Assuming you have a friend with a lathe. However you ream it, the case needs to be fully contained or the brass will just push away. Just a thought.
Paul

 

[NorCalMikie]

Either push the donut to the outside and turn it off OR, seat the bullets ABOVE the donut. Problem solved.

 

[Webster]

Why can’t you push it to the outside and then re-turn the neck?

I would quess that if the donut is only a few thou high the entire area would get pushed outward then spring back. Some people have the crazy idea that a mandrel will push tiny high spots to the outside of the neck. I assume that a donut is created by shoulder metal getting pushed forward thinning the shoulder/neck area.

 

[243winxb]

FL size, standard die. Expand neck. Outside turn.

 

[chomondely3]

Thanks for the ideas and the wisdom. Two of the forum members have kindly offered to help with the annealing process.
As to the donuts. I will try seating the bullets out a bit. I have room before jamming. At 600 yds, I consistently get 2 inch groups or less, assuming excellent (rare) conditions. So I am pretty happy with the load. Perhaps I can move the bullets out a bit.
I will probably anneal, and relegate these pieces of brass to shorter bullets i.e. Berger columns and shoot at a shorter range where he mirage is not as brutal in the Houston summer heat.

 

[NorCalMikie]

As to the donuts. I will try seating the bullets out a bit. I have room before jamming.

So, that means you load with a "jump" to the lands?
I load everything jammed .010 "into the lands".
Say 28 grains of XXXX powder loaded with a jump to the lands? At one point you'll start seeing pressure signs.
Now with that exact same load "jammed" into the lands, you can go past that powder charge and beyond till you start seeing pressure signs again.
I do have an advantage as all my chambers are cut with zero freebore just so I can jam into the lands and, as the throat wears I can still reach the lands. YMMV.