How to identify donuts

[anaconda]

What are some ways to identify donuts? I turned necks with 21st century lathe for my 7mm rem mag. I turned down to .012 per side after recommendation to have .004 clearance. I did slightly cut into shoulder junction. What are the chances of donuts still forming. Can the donuts be visually seen or am I just paranoid? What led me to this is after fireing and resizeing if I drag my nail across the shoulder junction I can feel a lip. I'm full length sizeing with a honed forster die then expanding necks with a mandrel. Any help is appreciated this is my first rodeo with neck turning. I can upload pictures if they will help thanks

 

[Rodney]

If you're expanding the necks with a mandrel, you should be able to see them on the outside of the neck. The mandrel would push them to the outside. That's my process when I turn necks to put all imperfections to the outside so the cutter can remove them. Might be a little harder to see donuts if you neck size with a bushing only, because the donut would be on the inside of the neck. I'm relatively new to neck turning so I might be telling more than I know. Hope this helps or makes sense at least.

 

[riflewoman]

Most of them look something like this

 

[riflewoman]

But in all seriousness. The easy way is to take a small drill a thousandth or two under bullet diameter and see if the shank end rubs on the fired case neck on the inside.

 

[jimmymac]

...or the mandrel from a Lee collet die.

 

[anaconda]

These are once fired and sized

 

[expiper]

or ,,,just take a bullet and see if it will slip in the case neck all the way thru the donut area,,,if it goes to the bottom of the neck and "sits" there ,,,you have donuts,,,,but that is not a problem unless you seat the bullet to that point,,,I usually try to stay .020" or more above this point,,,,I save a case with a donut and sit the bullets that I use on the donut and record this measurement,,,this becomes my minimum ctg length with that particular bullet,,,,Roger

 

[jimmymac]

The donut is going to be on the inside of the case. That's where you need to check.

IMO, if you have donuts it's no big deal provided the base of the bullet falls above the donut after seating.

 

[jimmymac]

or ,,,just take a bullet and see if it will slip in the case neck all the way thru the donut area,,,if it goes to the bottom of the neck and "sits" there ,,,you have donuts,,,,but that is not a problem unless you seat the bullet to that point,,,I usually try to stay .020" or more above this point,,,,I save a case with a donut and sit the bullets that I use on the donut and record this measurement,,,this becomes my minimum ctg length with that particular bullet,,,,Roger

...beat me to it.

 

[anaconda]

Im right on the border of being seated in the shoulder junction. Those were expanded with mandrel so was wondering if maybe they could be seen on outside

 

[anaconda]

I can push bullet all the way. Maybe I'm just paranoid thanks for the help appreciate it. The feeling of the slight lip and extreme spreads led me to the idea of donut. Maybe I'll just have to try another bullet and see what happens unfortunately I have 1300 180 hybrids left can always use them in another barrel I guess

 

[mike a]

Most of them look something like this

The one with sprinkles is a creedmoor donut.

 

[Uncle Ed]

How many of you inside neck ream to remove donuts?

The You-Tube video below makes it look simple, but is there any downside to inside reaming vs other methods.

 

[Raythemanroe]

Most of them look something like this

Fritters can be a little wonky

Ray

 

[eas1949]

They are easy to identify. Chocolate, cake and glazed. As you can see they can be used as tuners also!

Eric

 

[jepp2]

just take a bullet and see if it will slip in the case neck all the way thru the donut area

expiper, my comment isn't directed at you, it is about what you shared. I often see the comment to see if a bullet will slip into the case neck of a fired case. My experience is that it rarely happens. The reason being the mouth of the case doesn't fully open as the rest of the case neck does. For example, my loaded 25-06 rounds neck OD is 0.282", the neck after firing is 0.290" OD. And this is how far a bullet will go into the fired case neck. A near max load.

 

[T-shooter]

Most of them look something like this

"Mmmmmmmmm Donuts!"

 

[Richard Coody]

if you use an expander mandrel in your sizing process or even an expander ball you will see the donut by the time they need adressing. then it is a simple process to run your neck turner and cut them out. running your neck turner into the shoulder certainly helps. thin that shoulder brass before it migrates into the.neck.

 

[gunsandgunsmithing]

Just don't size the neck all the way to the neck shoulder junction. Let it form on the outside and it'll help align the case in the chamber.

 

[BenPerfected]

K&M sells expander mandrels that are available in .0005 increments. You can buy them individually or in a full set. If you are concerned about neck tension and RO, these mandrels are the cat’s ass. The expander mandrel is my last step before priming, powder and bullet seating. Using a hydro press for bullet seating is my method for measuring consistent neck tension.
Ben