Quick question guys. My friend and son in law both are shooting Lapua brass in the 284s formed from 6.5x284 and both have donuts in the necks. My question is, "If I cut the donut out with my reamer will they return once they start shooting them again"??? I don't know if this will solve the problem or if the brass will need to be neck turned to stop it. Thanks Guys!!!
Cutting out Donuts???
- Thread starter Raptor
- Start date
DaveTooley
Gold $$ Contributor
It's just a fact of life donuts will form no matter what you do. Part of my shooting-reloading routine is to insert a bullet into fired cases checking for neck clearance and donuts forming. It's simple to have a chucking reamer +.001" over nominal bullet diameter to remove the donuts. Ream the donuts instead of cleaning primer pockets.
Keith Glasscock
Gold $$ Contributor
There seems to be very little that you can do to prevent them from coming into existence, or returning after removal.
The good news is they really don't matter as much as people would have you believe.
I am expanding and re-neck turning the brass I used at BSWN for the last two years. I'm removing a very large donut that seems to have had little effect on anything other than seating force. In the final inspection of the work I've done, I note that the diameter inside the donut is ~.0005 - .0010" smaller than the rest of the neck. It's a far cry from the .005+ it was.
The good news is they really don't matter as much as people would have you believe.
I am expanding and re-neck turning the brass I used at BSWN for the last two years. I'm removing a very large donut that seems to have had little effect on anything other than seating force. In the final inspection of the work I've done, I note that the diameter inside the donut is ~.0005 - .0010" smaller than the rest of the neck. It's a far cry from the .005+ it was.
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And to answer your questions. Yes the inside neck reamers chew out the carbon and makes it look pretty rough in the neck. I didn’t like what I saws seeing. The solution for not having enough freebore is to run a bullet with shorting bearing surface or lighter weight. Trust me. It will save you a lot of hard ache. I pretty much shot out a 6.5 wsm barrel trying to figure out what was going on. I was way into the doughnut and I learned a valuable lesson. But there was many times I wanted to take a sazall to the barrel during load development. Very inconsistent velocities. Virgin brass was way slow. The doughnuts got progressively worse with firing on brass.
One thing I do when I’ve marked up the inside neck is to burnish the surface with a bronze bore brush wrapped in steel wool. It will polish the surface slicker than new. Once it’s shot again, you regain the lubricity of a carbon coating.
Like stated above, the better approach might be to expand the neck and turn at the bulge and prevent the need to fool with the ID.
Gerald
We turn brass with a cutter that has an angle matching the shoulder (PMA). This allows you to put a healthy cut into the shoulder without worrying about separations. This has completely eliminated donut problems. Lately, however, we have been experimenting with no-turn 284 WINs and they have shot every bit as good as the turned brass versions. We do get a donut on the necked up 6.5x284 brass, but the bullet is seated .060" above it and accuracy is not affected.
PS. Dont recommend inside reamers. they cost extra, rough up the neck, and don't make the problem go away permanently. Outside turning (into the shoulder with correctly angled cutter) is way better IMHO.
PS. Dont recommend inside reamers. they cost extra, rough up the neck, and don't make the problem go away permanently. Outside turning (into the shoulder with correctly angled cutter) is way better IMHO.
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DaveTooley
Gold $$ Contributor
Interstate .2850" chucking reamer $26.00 MSC Direct I have them for 6MM-338
If you chew up the inside of the neck maybe you shouldn't be trusted with anything mechanical.
Not everyone wants to neck turn. For those that do, neck turning only delays the formation of a donut. Assuming your primer pockets last long enough.
Not everyone has long throats and have to deal with donuts.
So the body of the bullet is in front of the donut and your OK with variations in the ID of your necks.
YMMV
If you chew up the inside of the neck maybe you shouldn't be trusted with anything mechanical.
Not everyone wants to neck turn. For those that do, neck turning only delays the formation of a donut. Assuming your primer pockets last long enough.
Not everyone has long throats and have to deal with donuts.
So the body of the bullet is in front of the donut and your OK with variations in the ID of your necks.
YMMV
Dave, your correct!! Actually my cutter is .2850. On a fired case it just slides in until it contacts the donut. It only takes a couple of turns and the donut is gone. I see no scaring of the neck other than where it cuts the donuts out. In actuality the donut doesn't really seem to affect the accuracy all that much. I was really surprised when I was playing with his rifle. I purposely seated the bullets well into the donuts. The rifle runs more neck tension than most of you guys probably do since he is running a stock die set up. I am guessing around .006??? So maybe that it why the donut does not bother as much as it would with a couple of thousands of NT, just a thought. It was holding .5MOA at 300yds shooting off the hood of my pickup...
ronemus
Gold $$ Contributor
Letting donuts get long can lead to an unsafe condition if you have a close-necked chamber. The bullet will expand the neck (although the neck can swage the bullet to some extent). If the expanded neck causes a 0- or negative-clearance condition, pressures will skyrocket; in the extreme this could result in a KABOOM!
DaveTooley
Gold $$ Contributor
He maybe expanding the necks more than necessary but in the end he isn't getting any additional neck tension. The bullet acts like an expander ball. Once the bullet passes through the sized portion of the neck the amount of force required to seat the bullet is reduced. Obviously neck thickness and hardness play a role in neck tension.
Not in my experience with my 284 no turn neck, donuts form on first firing..
I wouldn’t as far as saying I shouldn’t do anything mechanical. The inside diameter of a fired case neck is smaller than the inside neck resmer I have from LE Wilson. To me it would be hard to ream the inside of a neck without knowing the neck diameter of a chamber, unless you only taking out a small portion, or you chew up some carbon....
dedeadeye
Silver $$ Contributor
Inside reaming can be tricky. Size the case. The trick is to expand the inside of the case neck with a Vermont pin gage (from Amazon Prime $5.00) .002 larger than the cutter tool diameter and stop when the pin touches the donut. Do not push pin past donut as that will push some of the donut to the outside. Now turn the case on the cutting tool IN REVERSE until you reach the donut. Now turn in the cutting direction or normally clockwise and cut through donut. Turn case back off the cutter again in reverse. By turning case in reverse to and from the donut will stop any damage to the inside of the case neck. May sound complicated at first but it is very simple after a few tries.
Roger Gower
Roger Gower
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The quick fix, if you don't foresee having .284 Brass available for the life of the barrel would be the Ream the Barrel Deeper past where the Donut would form. You would have to fire-form your brass as you would any "Improved" Cartridge. The drawback would be slightly shorter Necks. I'm no expert, but according the Diagram the shoulder on the 6.5 is .024" shorter than the .284. if this is correct, which is not a good thing for case life or case separation.
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