Weird Sizing Issue (making doughnuts)

[whatsupdoc]

If take a standard RCBS FL 223 die and simply resize the brass with the provided expander ball/decapping assy
installed a .221 pin gauge will slide completely through the case neck with no issue.

If it take the same die remove the decapping assy, resize the same batch of cases then push a mandrel through the case neck a .221 pin gauge will slide through the neck until it reaches the neck shoulder junction and stop dead. I have tried a different mandrel with the same results.

I am creating a doughnut Why?

 

[BoydAllen]

The expander pushed the doughnut to the outside of the case. Without it, it remained inside. Are the shanks of your bullets in the area of the neck shoulder junction? If they are, then the question is whether there is clearance in the chamber at that point. How much are you bumping back shoulders when sizing?

 

[Goes_Bang]

I'll take a shot.

Not enough float between the mandrel and the mandrel die assembly? The mandrel should be slightly loose in the assembly.

 

[whatsupdoc]

The expander pushed the doughnut to the outside of the case. Without it, it remained inside. Are the shanks of your bullets in the area of the neck shoulder junction? If they are, then the question is whether there is clearance in the chamber at that point. How much are you bumping back shoulders when sizing?

I understand that the expander ball pushed the doughnut to the outside but why does the mandrel not also do that?

As far as bullet shanks go, up to 69gr no problem as the shanks never go past the neck shoulder junction
but when I shoot 80gr bullets I have no choice the shanks go past the neck shoulder junction.

I am bumping the shoulder .002 back.

 

[243winxb]

Donuts can be there already in New brass.

 

[Uncle Ed]

What is the diameter of your dies expander ball and the diameter of the expander mandrel?

Meaning if the expander ball is a smidgen larger the pin gauge could pass through the neck.

And the drag of the expander ball could be pulling, stretching and thinning at the neck shoulder junction.

 

[whatsupdoc]

Expander ball and mandrel diameter are the same diameter, I am actually using a turning mandrel that is .001 smaller than a expander mandrel.

But I have also used a standard expander mandrel and had the same results only with a .222 pin gauge.

 

[AJC]

The lee collet neck die is cheap and I have read tons of reports that it is powerful enough to migrate brass. Might be worth a try.

 

[Uncle Ed]

How many times have these cases been resized, a fat chamber and a skinny die will cause more upward brass flow and increased donut growth.

And if you used a bushing die and raise the bushing and not size just above the neck shoulder junction a donut would not be a problem.

 

[Richard Coody]

Expander ball and mandrel diameter are the same diameter, I am actually using a turning mandrel that is .001 smaller than a expander mandrel.

But I have also used a standard expander mandrel and had the same results only with a .222 pin gauge.

Obviously the expander mandrel is not sizing all of the neck.

 

[Ned Ludd]

If take a standard RCBS FL 223 die and simply resize the brass with the provided expander ball/decapping assy
installed a .221 pin gauge will slide completely through the case neck with no issue.

If it take the same die remove the decapping assy, resize the same batch of cases then push a mandrel through the case neck a .221 pin gauge will slide through the neck until it reaches the neck shoulder junction and stop dead. I have tried a different mandrel with the same results.

I am creating a doughnut Why?

As you sequentially fire and re-size the brass, you are forcing metal to move/flow. Because of the physical constraints, it likes to accumulate near the bottom of the neck. To some extent, a steeper shoulder angle can help reduce this flow, hence this issue can be worse in cartridges with shallower shoulder angles.

Regardless, the primary movement/flow of brass occurs when you re-size the case. If you use the expander ball in the die, you are mitigating the donut issue even as you cause it, re-displacing any metal that has accumulated to form the donut as the expander ball goes down through the neck on its way into the case, and and even more so on its way back out after the case has been fully re-sized. When you remove the expander ball, there is nothing to mitigate donut formation as the case is re-sized. Thus, when you then try to run a mandrel down into the neck, the donut will be clearly felt. This is not to say one way is better than another, only different in that expansion of the neck from the inside by the expander ball is concurrent with the re-sizing process, whereas running a mandrel into the neck after you have re-sized a case using a die without the expander ball is a sequential process.

 

[whatsupdoc]

Obviously the expander mandrel is not sizing all of the neck.

I have a window milled out of the mandrel die so I can see how deep the mandrel enters the case
and it clearly goes through the entire neck of the case.

As you sequentially fire and re-size the brass, you are forcing metal to move/flow. Because of the physical constraints, it likes to accumulate near the bottom of the neck. To some extent, a steeper shoulder angle can help reduce this flow, hence this issue can be worse in cartridges with shallower shoulder angles.

Regardless, the primary movement/flow of brass occurs when you re-size the case. If you use the expander ball in the die, you are mitigating the donut issue even as you cause it, re-displacing any metal that has accumulated to form the donut as the expander ball goes down through the neck on its way into the case, and and even more so on its way back out after the case has been fully re-sized. When you remove the expander ball, there is nothing to mitigate donut formation as the case is re-sized. Thus, when you then try to run a mandrel down into the neck, the donut will be clearly felt. This is not to say one way is better than another, only different in that expansion of the neck from the inside by the expander ball is concurrent with the re-sizing process, whereas running a mandrel into the neck after you have re-sized a case using a die without the expander ball is a sequential process.

Ok I got you, thanks.

I have played with this issue to try and verify the cause and find a possible (simple) solution.
You are 100% correct when I slide the case out of the mandrel you can definitely feel the drag of the doughnut until the mandrel ogive clears it.

I tried reaming the inside of the neck and it works but is a pain in the butt. Another way that seems to
work is multiple passes into the mandrel that irons out the doughnut.

So what is the general consensus for removing doughnuts reaming?

 

[Ned Ludd]

I have a window milled out of the mandrel die so I can see how deep the mandrel enters the case
and it clearly goes through the entire neck of the case.



Ok I got you, thanks.

I have played with this issue to try and verify the cause and find a possible (simple) solution.
You are 100% correct when I slide the case out of the mandrel you can definitely feel the drag of the doughnut until the mandrel ogive clears it.

I tried reaming the inside of the neck and it works but is a pain in the butt. Another way that seems to
work is multiple passes into the mandrel that irons out the doughnut.

So what is the general consensus for removing doughnuts reaming?

It's a .223 Rem case. I personally wouldn't worry about a donut. Years ago, I started loading heavy .224" bullets (80.5 gr) for an F-TR practice rifle that was chambered with zero freebore. As you can imagine, the bullet bearing surface extended well below the bottom of the neck. I remove the expander ball from all of my dies and feeling the "resistance" of donut when seating bullets in fired and re-sized brass at first caused some concern. However, I've loaded rounds for that rifle for years with the donuts and it shoots very well indeed, donuts or no donuts. I just haven't been able to generate solid evidence that the donuts are hurting anything, even though like you, I really thought initially that they would be a problem.

I have more recently started working with .224" bullets in the 77 gr weight class. Although lighter in weight than the 80-90 gr bullets, the ones I have been working with have a very long bearing surface, with a short stubby nose. The point being that even with commercial ammunition, the boattail/bearing surface junction of a 77 gr bullet loaded in .223 Rem case at mag length is stupidly far down inside the case; well below the bottom of the neck. If you wish to reload for the .223 Rem with even moderately heavy bullets and don't have the rifle chambered with exceedingly long freebore so that you can seat the bullet boattail/bearing surface junction well up in the neck, this is simply something you're going to have to live with. Of course, handloads with the bullet base seated above the donut will simply have to be single fed, they will be much to long to feed from a magazine. You can certainly try to ream out the donut, but if the load continues to perform well without going to that length, why do it? It took a lot of effort as I am very OCD about the reloading process, but I eventually stopped worrying about the donut. You might consider leaving the donuts alone and seeing how the load(s) actually perform before going too far down the road of trying to remove them.

 

[ronemus]

So what is the general consensus for removing doughnuts reaming

Reaming doughnuts can be done, but it's a PITA and difficult to do well. I find that it's easier to use an expander (in the size die or a mandrel) to move the doughnut to the outside of the neck and then turn it; alternatively, if your chamber has the clearance you could simply ignore it (in a SAAMI chamber with typical brass the doughnut on the outside is no issue)'

 

[mikecr]

Stop FL sizing necks/donuts

 

[243winxb]

Use a bushing die.

 

[piie]

I understand that the expander ball pushed the doughnut to the outside but why does the mandrel not also do that?

As far as bullet shanks go, up to 69gr no problem as the shanks never go past the neck shoulder junction
but when I shoot 80gr bullets I have no choice the shanks go past the neck shoulder junction.

I am bumping the shoulder .002 back.

This *could* also just be simply due to the shape of the Expander vs the shape of your Mandrel - your expander probably have a gradual increase in diameter - meaning it can pass through the donut and then gradually size it - whereas your mandrel might have a uniform diameter and will stick when it reaches the donut?

 

[Richard Coody]

Well what is the intended use of your rifle? It seems using a full length resizing with the expander ball eliminates you problem. Is there some reason why that method creates unacceptable ammo? That has been the most common method of sizing for many decades.

 

[The boogalorian]

 

[Uncle Ed]

Size the case and then skim turn the necks, when you get close to the neck shoulder junction you will start cutting off the donut. Then put your pin gauges back in the box and turn off the OCD.

Or use a bushing die and not size the base of the neck leaving the donut out of the equation.

RELOADERS CORNER: FOUR FIRINGS IN: FINAL​

GLEN ZEDIKER
Yikes. Gremlins. Case neck “donuts” are a common development in an aging cartridge case, and it’s often unknown. Read this and know!
http://www.mssblog.com/2019/04/04/reloaders-corner-four-firings-in-final/

This helps! Turning a tiny bit off the start of the shoulder gives some relief in this area and holds off the donut for at least a while.