Donut issue?

[ar10ar15man]

the wilson off the shelf is no good for donuts..its 311 based on stock fired case, not neck sized or turned match brass
send them 3 cases they will make a custom reamer.
donuts are at the shoulder..not the neck

 

[Reloader222]

Foster manufacture inside neck reamers. You use it before sizing the case. I have found it to be excellent in cutting away the donut and it does not damage the inside of the case neck at all. Some brass are more prone to donut forming and some less. It is usually those cases with lower inside capacity that produce donut more frequently. Some even after the first firing. The only problem with donuts is when you seat bullets below the shoulder/neck junction it would cause additional pressure which would change the point of impact. The best thing is to make it part of your reloading routine to check for donuts before sizing - even good brands like Lapua and Norma.

 

[Randy Tidwell]

In my experience, because of the shape of the cutters on the neck turning tools, neck turning does not completely remove the donut. I've never been able to remove a donut complete by turning the neck.

I've gone as far to have a reamer for my 6mm PPC stuff ground with a step in the middle. Minor diameter is .241, major diameter is .2425. Net is a perfect fit. Drawing attached.

By using the pin gauges, you can feel the donut at neck should junction. When the pin fits correctly, you get a popping sound from the vacumn release when you pull the pin out (primer still in place or hole covered). If the donut has not been remove completely, the pop happens before the pin is still in the neck.

 

[FamilyH]

I think I have a donut issue with my Nosler 300 rum brass. Basically, I tried to seat a bullet and it would go in smooth then get real tight at bottom. I had two that the bullet just hit a brick wall and would not seat any further. The brass is 2 or 3x fired. This is my process:

Uniform flash holes and primer pockets if new
Clean necks
Neck size and deprime with Wilson dies
Clean primer pockets
Bump shoulder and body size with Redding die
Trim after each firing
Debur and chamfer
Seat primers
Load
Seat bullets with Wilson dies

So what causes donuts? How can they be avoided? Were they due to loads being too hot or soft brass? Can you get rid of them with expander mandrel?

Thanks,

DoubleG

I have had this happen to me. What is going on is the case is flowing forward when you fire it in your rifle, to get rid of the donut you need a inside neck remember fo your caliber.

 

[bigedp51]

Foster manufacture inside neck reamers. You use it before sizing the case. I have found it to be excellent in cutting away the donut and it does not damage the inside of the case neck at all. Some brass are more prone to donut forming and some less. It is usually those cases with lower inside capacity that produce donut more frequently. Some even after the first firing. The only problem with donuts is when you seat bullets below the shoulder/neck junction it would cause additional pressure which would change the point of impact. The best thing is to make it part of your reloading routine to check for donuts before sizing - even good brands like Lapua and Norma.

The above method will work and not chew up the entire inside of the case neck and just remove the donut. I would never ream the entire neck because it will become very rough and can leave spiral marks inside the neck.

Neck turning the necks makes the donuts worse and a expander mandrel helps push the donuts to the outside of the neck.

 

[Randy Tidwell]

the wilson off the shelf is no good for donuts..its 311 based on stock fired case, not neck sized or turned match brass. Send them 3 cases they will make a custom reamer.
donuts are at the shoulder..not the neck

I agree completely, that is why I have reamers custom ground for my applications. Most any grind shop can do it and you can get it right away.

The above method will work and not chew up the entire inside of the case neck and just remove the donut. I would never ream the entire neck because it will become very rough and can leave spiral marks inside the neck.

Neck turning the necks makes the donuts worse and a expander mandrel helps push the donuts to the outside of the neck.

That's why I have the reamer ground in two steps. First step cuts the bulk of the donut, second step cleans the cut almost to a mirror finish.

Never Ever Ream the inside of necks, that practice was abandoned by most many moons ago.

JMHO