Neck Buldge (INSIDE?) in 6PPC Brass?

[AR10T308]

My experience with creating 6PPC brass with the correct neck dimension is very limited, as I just purchased a couple of these guns on this forum this year, which I LOVE. I recently prepared and used some Lapua Russ 220 brass that appeared to function just fine in the rifle, BUT then when I went to reload them, I discovered that there was a very slight bulge INSIDE the bottom of many of the necks (where the neck meets the case body) that made it difficult to press the 6mm expander in the die back through the case neck during reloading without a LOT of force on the press.

What did I do wrong? I am hoping those with much more experience can help me diagnose my problem or error in the neck trimming and forming process.

The barrel is .262, and I had trimmed the Lapua brass necks so they all were between .0086 and .0089 in thickness. (Sorry, edit, I was off by a decimal)

Thank you,
Clay

 

[Firearmsunlimited]

Are you saying that you turned the necks to about 8 1/2 on average?

 

[AJC]

Search for donut and you will find tons of info

 

[AR10T308]

Search for donut and you will find tons of info

Got it. Thanks.

 

[Roeder]

You discovered what is known as "The Dreaded Donut". This is only a problem if you seat your bullets deep enough to interfere with it. Few PPC shooters use a neck expander after the initial brass prep, they either use a bushing die or a custom die that sizes the neck just right without needing to be expanded again.
If you must seat bullets into the donut, you need to either ream it out or expand it enough to turn the excess brass off the outside. It helps to cut slightly into the shoulder when neck turning, but there is no way to avoid the donut forming after several firings and for most Benchrest shooters it is not an issue.

 

[AR10T308]

Are you saying that you turned the necks to about 8 1/2 on average?

Trying for slightly over that at around .0086, but I am not great yet at having them consistent enough, or I don't have the ability to measure accurately enough out to that fourth decimal place.

 

[Firearmsunlimited]

My guess would be that you are experiencing the "dreaded donut" caused by not kissing the shoulder enough when you neck turned the brass. Since you have put time and expense into Lapua brass you should probably remove the donuts rather than pitching the brass and starting over. Removing the donuts correctly takes time and some expense.

 

[AR10T308]

You discovered what is known as "The Dreaded Donut". This is only a problem if you seat your bullets deep enough to interfere with it. Few PPC shooters use a neck expander after the initial brass prep, they either use a bushing die or a custom die that sizes the neck just right without needing to be expanded again.
If you must seat bullets into the donut, you need to either ream it out or expand it enough to turn the excess brass off the outside. It helps to cut slightly into the shoulder when neck turning, but there is no way to avoid the donut forming after several firings and for most Benchrest shooters it is not an issue.

Perfect. Great info. Thank you.

 

[AR10T308]

My guess would be that you are experiencing the "dreaded donut" caused by not kissing the shoulder enough when you neck turned the brass. What brand of brass has been affected?

Lapua 220 Russian.

 

[Ccrider]

No one has mentioned it but .0089 is too close for a .262 neck. If you err, make it .0085 or .0084.

 

[djporter]

My experience is if your bullet does not seat into the donut get a Harrels FL bushing die and toss the expander.

 

[AR10T308]

No one has mentioned it but .0089 is too close for a .262 neck. If you err, make it .0085 or .0084.

OK. Thanks, CC. So I should be shooting for .002 less than the barrel and there is nothing to be gained by trying to go slightly tighter? After some additional help and guidance today, I also know I need to get a mic for the necks to get more accurate measurements.

 

[tmwinds]

I don't think all is lost. Since you certainly need to skim the necks to .0084-.0085 as CC noted. This would be a good opportunity to use your mandrel to push the donut to the outside and turn it off. Also cut slightly into the neck shoulder junction when you do this. That will help delay the forming of the donuts.

 

[Link]

I don't think all is lost. Since you certainly need to skim the necks to .0084-.0085 as CC noted. This would be a good opportunity to use your mandrel to push the donut to the outside and turn it off. Also cut slightly into the neck shoulder junction when you do this. That will help delay the forming of the donuts.

And use plenty of lube while expanding.

 

[AR10T308]

I don't think all is lost. Since you certainly need to skim the necks to .0084-.0085 as CC noted. This would be a good opportunity to use your mandrel to push the donut to the outside and turn it off. Also cut slightly into the neck shoulder junction when you do this. That will help delay the forming of the donuts.

Thanks.

 

[Ccrider]

And use plenty of lube while expanding.

Expanding what?

 

[Dusty Stevens]

They should be turned again after the first firing and then get rid of the expander

 

[Ccrider]

OK. Thanks, CC. So I should be shooting for .002 less than the barrel and there is nothing to be gained by trying to go slightly tighter? After some additional help and guidance today, I also know I need to get a mic for the necks to get more accurate measurements.

You are correct. There is a lot of info out there on this. In Jim Neary’s video series he talks about cutting them thin to win. Long and short of it is that if your neck is too tight it will not expand enough to cleanly release the bullet. Also, it can cause over pressure which could be dangerous. I have shot brass turned from .0086 to .0079 and they all shot consistently. What is important is to turn them enough and to the same size. If not, you will have problems maintaining consistent neck tension

It takes some experience and good equipment to turn down to within .001 or .0005 consistency repeatedly. Neat thing is, it’s just brass. Easily replaceable and not intended to last indefinitely any way. I suggest starting off with 10 to 15 pieces. Turn them down to your desired thickness and give them a run. After your shoot them a few times, remeasure them. Clean them up if needed.

Just do it. Don’t fret any of it. Just ask and listen to the experienced guys on here. They have helped me immeasurably and made my ride down towards the bottom of the bottomless rabbit hole a quite enjoyable and insatiable experience.

 

[Link]

Expanding what?

The donuts out.

 

[AlNyhus]

Couple of suggestions:

On a fired case with a 'donut', the best results will be from removing the 'donut' with the neck in as-fired condition. You want to be very careful not to touch the inside case neck with the cutter/reamer...just remove the 'donut'. This takes a bit of precision measuring to get the correct cutter/reamer but it's worth the effort.

Don't try to measure neck thickness and extrapolate that to the final number with a seated bullet. The only number that matters is what the neck O.D. measures across the base with a seated bullet. Comparing that to the chambers neck diameter gives you the clearance number.

Good shootin'. -Al