The 284 "Donut"

[jr600yd]

Ok, sized some 6.5/284 Lapua brass up to 7mm. Necked turned them so I have .004-.005 neck clearence, (.313 neck) full length sized 'em loaded them and shot some Berger 180 Hybrids. Everything worked fine.
FL sized them for a second firing (.002 bump) and now have the dreaded donut. So the question is how do I eliminate the donut? I could get an inside neck reamer and cut it out. I could leave it alone since it's below the bullet base but I was thinking?
Could I use the neck turner and cut into the case shoulder some? Would the next firing then blow the donut to the outside of the case thus eliminating the problem?

What do you guys think?

 

[Jay Christopherson]

you can mandrel them out or you can seat above them. Those are the two best options in my experience.

You can ream them out as well, but I've never had luck with that. I just end up messing up my brass and it's tedious (for me).

 

[potatoe]

If your seating above it I'd leave it alone. I have this with one of my .284s and the accuracy is not effected.

 

[Keith Glasscock]

Ditto, just seat above them.

 

[Stralyanshooter]

If you shoot 284 you don't have to neck up brass anymore.

 

[Stralyanshooter]

That's a big plus for using straight 284 brass. We have some excellent quality brass is available to us down under made by Bertram as you all have Norma 284 brass. No necking up so no donuts. Too bad Winchester stopped producing it but now I can't see any reason to be necking up Lapua from 6.5 x 284 to 284.

 

[Killick]

... but now I can't see any reason to be necking up Lapua from 6.5 x 284 to 284.

Except for the fact that Bullets won't ship brass to Cali-gulag-ia...but Powder Valley will. PV has fewer lawyers I guess.

 

[Pappy42]

And except for the fact that I have a whole bunch of 6.5-.284 brass left over from from another project.

 

[markgrabowski]

And except for the fact that I have a whole bunch of 6.5-.284 brass left over from from another project.

I had the same issue with my30-284. I wound up taking a skim cut on the neck but continued into the neck junction. Seems fine now

 

[Pappy42]

I had the same issue with my30-284. I wound up taking a skim cut on the neck but continued into the neck junction. Seems fine now

Yep, I think that Mr. shootsdots told me to cut them all to length, mandrel them to push the donut to the outside, and cut past the neck, into the shoulder approximately 1/32". I use a K&M carbide cutter with correct shoulder angle.

 

[Cowtownup]

to the OP... do you think the donut was caused by not having ample freebore?

 

[Pappy42]

to the OP... do you think the donut was caused by not having ample freebore?

I don't know if this was meant for me, if so, I don't have a clue. All I know is that my rifle shoots great, the bolt operates with ease, closing and opening after firing (BAT action).

 

[Cowtownup]

Yeah I'm just trying to learn the cause of the donuts. Curious if it was due to the boat tail being seated below the neck shoulder junction?

 

[jr600yd]

I doubt free bore is a problem. My chamber has 220 just to shoot the 180's

 

[potatoe]

Free bore won't cause a doughnut, but having longer free bore to seat bullets above the doughnut eliminates the effect of the doughnuts.

 

[Raptor]

Would someone please explain to me what actually causes a "Doughnut"?? Do you have to size "Up" to get the doughnut or can you get one by using the correct size of case to start off with"?? Final question, "How do you know if you have a doughnut"? Thanks guys!!!!
"

 

[Pappy42]

I know that they are there when the fired case will accept a bullet in the neck but won't drop thru the neck/case junction.

 

[furmaster]

Would someone please explain to me what actually causes a "Doughnut"?? Do you have to size "Up" to get the doughnut or can you get one by using the correct size of case to start off with"?? Final question, "How do you know if you have a doughnut"? Thanks guys!!!!
"

A donut is caused from the thicker brass of the shoulder flowing into the thinner brass of the neck. It can be caused either with a neck turned cartridge making neck thinner, sizing up brass creating a thinner neck or both at the same time. If I'm not mistaken lapua brass in 6.5 284 is thicker on the shoulder to start with.
I run the exact same chamber. Virgin brass...I use km mandrel to size up, load and shoot. Fired brass, run through full sizer, run mandrel in neck, use km turner/reamer, neck size with .307 bushing,load and shoot. That is a lot of work for that brass to go through, I anneal every third firing.

 

[Sean Haggerty]

If you are necking up 6.5x284 brass do you always need to neck turn. I have two barrels that are savage drop in one from shilen (sammi) and a match chamber from criterion. Thanks

 

[Killshot]

I faced this same issue this month. Even though I'd have to be seating with .090"+ jump for the donut to affect seating I wanted to remove them.

After reading thru the old threads here, I decided to order a Chucking Reamer sized .2845" with six flutes to remove them.

Using a K&M Shellholder chucked into a drill to hold the case (and the drill held in a vice) and a tap-handle to hold the Chucking Reamer (which is tapered 45º at the entry end) it slides into the case and then cuts out just the donut. I first tried a .2840" chucking reamer but it only removed 90% of the donut so I ordered the .0005 oversize - works great for those with no-turn necks using necked-up 6.5x284 brass.