what happens to the donuts if you don't neck turn it off??

[Ogre6br]

HI
What happens to the "donut" if you just neck cases up load and fire without neck turning the "donut" off???

Where does it go?? Does it cause problems with the brass?

Thanks

later
p

 

[NeilNE]

Its goes inside the neck. As long as you seat bullet above the donut you are OK. If you seat on or a portion of the bullet on the donut you can have big problems.

 

[M700]

Shorter bullets avoid this - I have no problems with my .308 when loading 155 grain bullets instead of 168's or 175's. The longer bullets run into the doughnut and I can feel it when I seat the bullets.

Same thing with the .25-06 when I neck size - the 100 grainer seats above the doughnut.

When I'm using standard RCBS full-length resizing dies I never notice a doughnut because it's ironed out by the sizing process, becoming just excess length to trim off I suppose...

FWIW, Guy

 

[BillPa]

I think dounts are more common than some realize. Why some cases develop them while other don't is a mystery to me. Of the last batch of 50 250-3000AI brass I formed 10 or so had donuts to some degree. Its a .283" chamber with the neckes turned to a finished .2815"
I deal with them a couple ways. Fastest and easiest is to have a inside reamer cut to the finished ID of the neck,size the necks and ream, Dounts-B-Gone. I use a Wilson trimmer to cut them. The problem doing it this way is you'll end up with a few different sized reamers if you play around with neck tension. Another way, use a K&M mandrel. Sometmes I'll expanded the necks to push the excess brass to the outside and turn them.

As long as your bullets are seated out past the neck-shoulder junction, they aren't a problem, except if you using a standard die with an expander then you may rip the press off the bench as the ball is pulled over it. But, if the bullets are seated deep into the junction, its a good idea to check for them.

After this one, I religiously check anytime the bullets are seated deep. In this case it was a 270-308AI.

 

[StephenPerry]

Donuts
I feel just leave the donut alone. If outside neck turn and then remove the donut you might have a neck separation where the donut was removed. Your only problems are if you seat bullets deep enough to contact the donut or your knock-out pin will not pass through. Enjoy your shooting forget the donuts. If neck turning next time cut a scoosh into the shoulder.
Stephen Perry

 

[Ogre6br]

question was asked as I'm going to begin to form some 30 BR's soon

later
p

 

[tightneck]

After you neck up your 6br brass to 30, your next step would be to FL size the case to insure the neck be paralell with the body of the case. I dont shoot 30br but I would think the same principles would hold true for donut forming in 6ppc + 6br. Ive found that if I run the case as high as I can in my fl die, I will push the shoulder back as much as .015. This creates a false shoulder at the neck/shoulder junction. If you run your neck turner all the way back to this false shoulder, when you fireform your brass, there will be no possibility of a donut forming. Ive found with both 220 and 6br Lapua brass that the cases just dont stretch very much over the life of the case and I havent run into a case where the thicker brass has crept out to the neck of the case.

 

[AlNyhus]

ogre6br:

When you neck a 6BR case to .30, there is a resultant external 'donut' just above the new neck shoulder junction. This happens because the new .30 cal. neck/shoulder junction is now what was formerly all shoulder on the 6BR case..and the shoulder is considerably thicker than the neck.

Now...this 'donut' measures .336 when expanded with a .308 mandrel and is approximately .050 long. The case neck itself,ahead of the donut) measures .331 w/o a bullet seated and with a neck i.d. of .306. In other words: if you seat a bullet into an unturned 6BR case necked to .30 cal, the neck o.d. will be around .333 and,assuming the bullet is seated into the donut area) the donut O.D. will be around .338 O.D.. Even if the bullet doesn't go down that far, you're still looking at needing a chamber neck diameter of .337-.338 to safely acommodate the external donut.

So...are you saying that the neck diameter of your chamber is .338 ? I've seen a lot of 30BRs, but I've never seen one with a chamber neck of that diameter!

I've attached a picture of a necked up 6BR Lapua case. You can clearly see the 'donut' above the new neck/shoulder junction that measures .336.

The bottom line is: what is the neck diameter of your chamber?

 

[Ogre6br]

Al Et all

Does the donut still form if you fire form with COW without necking up??
What's your opinion on using a fireforming barrel and keeping the good one for after the brass is formed.

I'm looking more towards a .334 or .336 neck.
Just depending on which gunsmith I go to for the job.


Thanks for the explination and the pic.

I'm not new to reloading but I'm new to this more advanced stuff.

Thanks

later
p

 

[AlNyhus]

We've messed with fireforming 30BR's using no bullet and a fast pistol powder and a wax plug, but have discontinued this practice. It still takes a 'real' bullet to fully form the case, so we just load 'em up and fire 'em now.

I would discourage you from trying to make a chamber neck over .330 work...maybe .331 as an absolute max. The .330 necks have been proven to be about the max. you can have and still clean up the necks properly.

These 30BR's are about the simplest case I've ever worked with....I've made well over a thousand 30BR cases for quite a few rifles. Straying from the basic, well proven concepts, dimensions and parameters proven in competition will only limit the success of your project.

Just my opinion on it. Good shootin'. -Al

 

[Aussie_bob]

Well there you go OGRE so what do you reckon send me some new lapua Brass and i will neck them up and turn them for you for no charge just coz i want to see you get this project completed OK