Bushing sizer = Doughnut????

[fatelvis]

A two part question for you guys:
1) If I don't neck turn my brass, is there any chance of developing a doughnut in the neck/shoulder junction?
2) Does the use of a standard sizing die eliminate the chances of a doughnut over a bushing die?
I ask because I may or may not turn my necks, and if I do, I'm trying to avoid the dreaded doughnut.
Thanks guys

 

[Dusty Stevens]

Yes
No

 

[hogpatrol]

Loosely related but what cartridge, chamber neck diameter and loaded round diameter? Turning necks for gp isn't always a good practice.

 

[LA50SHOOTER]

A two part question for you guys:
1) If I don't neck turn my brass, is there any chance of developing a doughnut in the neck/shoulder junction?
2) Does the use of a standard sizing die eliminate the chances of a doughnut over a bushing die?
I ask because I may or may not turn my necks, and if I do, I'm trying to avoid the dreaded doughnut.
Thanks guys

To expound a little bit.
Cause of the dreaded doughnut is from brass flowing forward during the firing process. Cartridge cases that have a lesser shoulder angle are more prone to this condition than those with sharper shoulders. BUT, even a sharp shouldered cartridge can experience the doughnut condition when not correctly neck turned.

If having best accuracy is a concern, I’d recommend that you start with high quality brass and plan to neck turn, and have the barrel chambered accordingly for the planned neck turned brass.

Also, if the leade is set correctly to keep the bearing surface / base of the bullet above the neck shoulder junction then the significance of the dreaded doughnut is basically negated as the bullet bearing surface is above this point and not in contact with the spot where doughnuts occur.

Any brass if fired enough times can have the case necks thicken a slight amount and a “skim pass” with the neck turning tool can return the thickness back to the desired thickness specifications.

It will all depend on how tight of tolerance that the user wants to maintain. I like to have uniform neck tension on most of the cartridges that I shoot so I neck turn and anneal my brass. As well, the chambers are cut with a finisher chambering reamer that is a good match for the brass that I use after it is neck turned.

Regarding dies, they do not directly create doughnuts, the doughnut is created through brass flowing forward to the neck shoulder junction. Improper use of sizing dies can accelerate this condition as well as contribute to run-out issues which is another topic all together.

- Ron -

 

[Tim Singleton]

I don’t believe brass “flowing during firing” Is accurate
the brass moves during sizing, over sizing is the biggest contributor to the doughnut

 

[243winxb]

This new 223 brass seems to come from the factory with donut included.

A great photo from- https://www.ampannealing.com/articles/42/annealing-under-the-microscope/

Avoid the donut, use a bushing die and dont size all the way to the neck. Or outside neck turn.

 

[fatelvis]

Thanks guys. Just a little info in case it matters:
I’m rebarreling my Rem 700 with a Criterion Remage 223 barrel using the “223 Match” chamber. I’ll be using it with 77-85.5 grain bullets for F-class. I’m thinking of turning the Lapua brass necks just enough to even them up.

 

[LA50SHOOTER]

I don’t believe brass “flowing during firing” Is accurate
the brass moves during sizing, over sizing is the biggest contributor to the doughnut

So.... The brass doesn't move when it's fired.... (Not) - We know that it "moves" both when sized by a die and when it recon forms to the chamber.

 

[243winxb]

For the 223, neck turn the donut off. Then the 77-85.5 grain bullets can be seated deeper. Shorter COL to fit the chamber.

You may need to order a special chamber?


Read- http://forum.accurateshooter.com/threads/chamber-too-short.3989444/

 

[Iowa Fox]

Thanks guys. Just a little info in case it matters:
I’m rebarreling my Rem 700 with a Criterion Remage 223 barrel using the “223 Match” chamber. I’ll be using it with 77-85.5 grain bullets for F-class. I’m thinking of turning the Lapua brass necks just enough to even them up.

Give Jim at NNS a call and he will email you a reamer print while you are on the phone with him. Its been my experience that NNS chamber are generous with throat dimensions, I don't think you will have to do any neck turning even though its listed as a match chamber. Match just means throated for longer heavier bullets.

Another thing I have found is that if you use a Lee collet neck sizer using John Valentines instruction it tends to uniform necks somewhat especially on new brass. I squeeze them, turn a third doing them three times.

 

[Ned Ludd]

Thanks guys. Just a little info in case it matters:
I’m rebarreling my Rem 700 with a Criterion Remage 223 barrel using the “223 Match” chamber. I’ll be using it with 77-85.5 grain bullets for F-class. I’m thinking of turning the Lapua brass necks just enough to even them up.

If you decide to do it, lightly turning the necks, maybe even just a skim pass, is not going to hurt you. However, it is not necessary to turn the necks of Lapua .223 brass for F-TR if you have a no-turn neck chamber (0.252"-0.253" nk). Further, donuts are much more of a problem with some cartridges than others due to upper case wall thickness and taper, shoulder angle, and likely several other factors. Brass moves when you fire and re-size it, no way around that. However, the .223 Rem case is not really known for having a severe donut problem, even though you usually can "feel" the resistance caused by a small donut on brass that has been fired and re-sized a few times if you try seat a bullet way down deep in the neck.

The easiest way around a donut issue with the .223 and heavies is to have sufficient freebore in the chamber to allow the heavy (long) bullets to be seated with the bottom portion of the bearing surface well above the region around the case neck/shoulder junction. That way, it will never come in contact with any donut. If the boattail/bearing surface junction of a seated bullet is from 1/4 to 1/2 the length of the neck above the case neck/shoulder (i.e. bullet bearing surface occupies anywhere from 1/2 to 3/4 of the neck length, but not all the way down to the bottom of the neck), you shouldn't have any problem.

 

[Zero333]

The brass I size in standard RCBS FL dies with expender button does not get doughnuts.