First time annealing now I'm seeing the dreaded donut

[QTRMOA]

Well as luck would have it... I decided to anneal my 6.5 CM brass after its fourth firing from my bolt gun and to run it in my GAP10 gas gun.
Now after annealing I am seeing donuts on the neck shoulder junction that measure roughly .003-.005".
I am using Redding S bushing seizer followed by a FL body die.
I have used Unique case lube with no real effect
I have removed the expander ball with no real effect.
I am using a .003 S busing for my gas gun.
Is it possible that I got the brass to soft and now its forming the dreaded donut?

 

[Scott Harris]

I get donuts in all my Lapua cases after a few firings. The only thing I've found to prevent it is to turn the necks...into the shoulder. I use a cutter than matches the neck shoulder angle and cut a healthy amount out of the shoulder. As a result, my donut problems have disappeared. I have never had any neck shoulder separations in spite of taking a healthy chunk out of the shoulder. Your annealing may have sped up the appearance of donuts by allowing the brass to flow a little faster, but I think the donuts would appear anyhow.

 

[6BRinNZ]

I doubt that annealing is causing it. I had donuts long before I started annealing. If the bearing surface isn't into the donut I don't worry about them.

 

[Steve Blair]

I get donuts in all my Lapua cases after a few firings. The only thing I've found to prevent it is to turn the necks...into the shoulder. I use a cutter than matches the neck shoulder angle and cut a healthy amount out of the shoulder. As a result, my donut problems have disappeared. I have never had any neck shoulder separations in spite of taking a healthy chunk out of the shoulder. Your annealing may have sped up the appearance of donuts by allowing the brass to flow a little faster, but I think the donuts would appear anyhow.

[br]
I do the same as Scott and have no case problems. Lapua brass has a very thick shoulder and can easily take a little cutting. I believe that some Dasher shooters set back the shoulder of Lapua 6BR brass, turn the long neck all the way down and then fire form. This results is a fully "turned" shoulder and it doesn't seem to cause them problems.

 

[alf]

Now after annealing I am seeing donuts on the neck shoulder junction that measure roughly .003-.005".

I am using Redding S bushing sizer followed by a FL body die.

While you may have donuts too, beings a bushing die does not size all the way down the the neck/shoulder juncture, part of what you're seeing is the unsized portion of the neck.

 

[fdshuster]

Agree to the above: annealing has little or no effect on the formation of donuts. My factory brass that has never been annealed will have donuts beginning to form after the fifth or sixth loading, using both neck bushing dies and the traditional non bushing types.

I measure their location using the intended bullet and note that seated length that would leave the bullet contacting the donut, then make sure the bullet is seated in front of the donut, with no contact. This is one of the considerations when specing out a new chambering reamer: bullet touching the lands, with the full diameter of the bullet about .020"/.030" in front of the donut.

Have tried cutting them out with the carbide tool. Did not work. Then had custom inside neck reamers made (by Forster/ not cheap), did not work. Their diameters/thickness will vary so there is no way a fixed diameter cutter will remove them reliably. Too many variables.

Like qtrmoa, not everyone is outside neck turning, so unless you are, that is not the solution. So, my "fix" is to let them form, but be aware of bullet seating depth so there is no contact.

 

[spclark]

Annealing bottlenecked cartridge brass will probably speed up the apoearance of 'donuts' in case necks, if for no other reason than because you're softening the brass a little bit. That's the purpose of annealing, after all.

As others have suggested, the key is knowing when you ought not seat bullets into the 'donut zone'.

Neck turning - with a careful cut into the shoulder at the shoulder/neck junction - will help, as of course will inside-neck reaming.

It's all a matter of knowing what you're messing with & what to be watchful of lest something unseen or underappreciated spoil your fun.

 

[fdshuster]

spclark: Inside neck reaming may work for some, but believe me I had no success. Had parrallel sided reamers custom made by Forster in .001" increments. They were either too large in diameter to fit in the case neck (without removing case neck wall thickness), or too small so they overrided the diameter of the donuts. Not all donuts are created "equal" in thickness, but whatever cutter you attempt to use will have a fixed cutting diameter.

They are a real P.I.T.A to remove, so my "solution" is to just be sure the bullet is not contacting them. Works for me.

 

[kelbro]

What was the cost on the inside reamers compared to the cost of new brass?

 

[spclark]

Right FD, as with anything else there are +'s & -'s when you start down the neck reaming road.

Only significant experience I've had with it was while I was messing with making 6XC cases out of Lapua Palma brass parent stock. I used a stock Wilson reamer with my case trimming tooling of the same brand, had no issues & good concentricity, neck wall uniformity in the end.

Lot's of work, not recommended for the faint-hearted.

Donuts are better eaten with coffee than overcome by whatever means you feel is warranted!

Learning to live with 'em or figuring out how to avoid 'em in the first place are bowth better options by far!

 

[fdshuster]

kelbro: $78 for 3, one was a standard in stock diameter & 2 were special order customs. A big,disappointment when none would work.

I have used a jewelers needle file, quarter round to file the donuts out & it does work, but very time consuming if needing to do any large number of cases. For me, easier to just be aware of bullet seating depth versus the donuts. Lapua 220 Russian (for the 6ppc's) and 6BR is just too expensive to toss after 5 or 6 loadings, especially when they are good for over 40 trouble-free loadings. Bullet seating depth is my "solution".

 

[kelbro]

kelbro: $78 for 3, one was a standard in stock diameter & 2 were special order customs. A big,disappointment when none would work.

I have used a jewelers needle file, quarter round to file the donuts out & it does work, but very time consuming if needing to do any large number of cases.

I did the same but I used the Lee case trimmer shellholder tool to hold the case in my battery-operated screwdriver to spin it while filing. Redneck? You bet!

 

[Nodak7mm]

Just for sake of discussion, the OP should clarifiy the location of his donuts because I see the answers given to both; a Donut on the inside of the case neck and then what Alf is refering to as I would call an outside Donut.

I have experienced the "Ouside donut" as Alf is refering to being caused by the bushing not fully sizing the neck and causing the tight spot. I dealt with this issue this year and it kicked my butt trying to figure out its cause. I arrived at the same conclusion as Alf points out and the way to I chose to address it was to get a custom F/L die made for my chamber to make sure that part of the neck would get sized. My first reaction was to want to turn the neck down in that area, but after sectioning a case I saw that I may be getting the brass too thin in that area..

Now I am not in possesion of my new die yet...... Soon, but I am going to be watching to insure that this outside donut doesent turn into an inside donut, which then would be addressed with inside neck reaming.

So am I on right track...?

To the OP, by no means am I attempting to hijack, but rather get clarification on the same subject...

Rod

And hey, its above 0* today.... ;D Gonna break out the flip flops.... Maybe not, it is only +1* :-\

 

[1holeaddict]

What a joyfull hobby ;D ;D Seems like every good step we take causes a thorn in the side down da road. Kinda like getting married

 

[Luke_NL]

Fds , did you try using the reamer in conjunction with an outside neck sizing die with bushing? You probably did, but im puzzled as to why that would not work.

 

[rain164845]

Rod,
Maybe try outside neck turning before you FL size that brass and push the donut to the inside.

 

[lpreddick]

i have formed donuts while necking down brass? the brass is being pushed down and if it slightly "telescopes", it has to go somewhere...outside and inside. i have been very successful in reaming donuts using a wilson case holder and a wilson internal neck reamer. the case is held securely and the reamer passes into the neck very straight. a little brass is taken before encountering the donut, depending on which bushing is used to size the neck. you have to twist the reamers by hand and after doing 50 or more, i can get a hand cramp! the handle on the wilson case trimmer will not fit the reamer, which would make this a snap. i'm looking into having a handle welded to the base of a trimmer handle. an established donut is VERY HARD and can take some effort to remove as above and viewing the results with a borescope is interesting.

 

[Steve Blair]

i have formed donuts while necking down brass? the brass is being pushed down and if it slightly "telescopes", it has to go somewhere...outside and inside. i have been very successful in reaming donuts using a wilson case holder and a wilson internal neck reamer. the case is held securely and the reamer passes into the neck very straight. a little brass is taken before encountering the donut, depending on which bushing is used to size the neck. you have to twist the reamers by hand and after doing 50 or more, i can get a hand cramp! the handle on the wilson case trimmer will not fit the reamer, which would make this a snap. i'm looking into having a handle welded to the base of a trimmer handle. an established donut is VERY HARD and can take some effort to remove as above and viewing the results with a borescope is interesting.

[br]
If brass is being "pushed down", wouldn't that reduce neck thickness? I have never seen a neck thickness reduction, even when donuts form. [br]
As far as the donut being hard; wouldn't annealing restore the material condition?

 

[spclark]

... and after doing 50 or more, i can get a hand cramp! the handle on the wilson case trimmer will not fit the reamer, which would make this a snap. i'm looking into having a handle welded to the base....

Don't bother with that until after you try fitting a standard threading die wrench onto the Wilson reamer 'head'.

Yes, doing a number of cases will cramp your hand using the tool as it comes. When I embarked on making 100 6XC cases out of Lapua's new Palma brass I quickly realized I had to do something to make the reamer easier to use.

I found a standard die wrench to be adaptable to the task, though it's a press-fit onto the knurled reamer handle. I'd hoped the setscrew would be enough and that the die cavity (mine's six-sided, not sure a round one would work) would allow a slip-in fit, but in the handle I had laying around that turned out not to be the case.

Pretty much any means of increasing leverage ought to work. Unless you have access to welding/brazing tools, I'd think there has to be an easier/cheaper way.

If you go this route, be aware you'll have to make sure your Wilson trimmer's got sufficient clearance over your workbench top so the handle will clear. You probably don't need to ask me why I'm adding this tip.

 

[lurcher]

I have started bumping shoulders with a redding body die then neck sizing with a lee collet die with a washer over the case so only about 3/4 of the neck is sized, I was hoping this would negate the effect of donuts as they will form in the unsized portion of the neck. Will this donut avoidance approach work?