Neck Doughnuts

[Nanook4311]

Hello all,
New to forum, thanks for having me. Can doughnuts in the neck be avoided or minimized with proper annealing, keeping the case length at proper length, or use non-bushing dies? I have a 22-250 rem (no special chamber dimensions) and I use Redding Type S dies. Let me know if any other info is needed.

Thanks
Joe

 

[Evintos]

Pretty normal for bushing dies but you can use an expander mandrel die, FL sizing die with expander ball, necking turn, or ream the inside of the neck to get rid of the donut.

If you want to keep the Type S die, you can run an expander mandrel die (with proper size mandrel) from every few loadings or every loading.

 

[Nanook4311]

I’ve been looking at neck turning and mandrel dies, that would get me the most consistent neck tension. Would it best to use a FL sizer w/o the expander and a mandrel to set neck tension?

 

[whatsupdoc]

Never been able to completely push out doughnuts at the neck shoulder junction using a mandrel
with or with out annealing.

The only way that I have found to remove them is with a reamer or on a small lathe with a small
boring bar.

Are you using a pin gauge to check for doughnuts?


EDIT: It has been my experience that using a expander mandrel and a standard F/L die is worse than a bushing die and the pull through expander that comes with the die at making doughnuts.

 

[Nanook4311]

Never been able to completely push out doughnuts at the neck shoulder junction using a mandrel
with or with out annealing.

The only way that I have found to remove them is with a reamer or on a small lathe with a small
boring bar.

Are you using a pin gauge to check for doughnuts?

Way past that point, I can see them

 

[Evintos]

I’ve been looking at neck turning and mandrel dies, that would get me the most consistent neck tension. Would it best to use a FL sizer w/o the expander and a mandrel to set neck tension?

I can't say best but it's a very common method that has great results.

 

[Nanook4311]

I can't say best but it's a very common method that has great

It makes sense to me to FL size cause there is no “gap” between a bushing and the case shoulder to cause the doughnut. It also makes more sense to me to create the neck tension from expanding the inside diameter of the neck than “squeezing” the neck to get tension.

 

[straightshooter1]

It makes sense to me to FL size cause there is no “gap” between a bushing and the case shoulder to cause the doughnut. It also makes more sense to me to create the neck tension from expanding the inside diameter of the neck than “squeezing” the neck to get tension.

I find with my .308 and 6.5 PRC that a FL sizing die (like Forster's) with "no gap" without an expander ball, then use a mandrel along with having annealing the brass does a pretty good job at mitigating the donut problem. Even a little better, a Lee collet die works well on the neck, then use a body sizing die. But, the best and easiest solution I found for myself is to simply seat the bullet so the bearing surface is above the donut.

 

[hafejd30]

I find with my .308 and 6.5 PRC that a FL sizing die (like Forster's) with "no gap" without an expander ball, then use a mandrel along with having annealing the brass does a pretty good job at mitigating the donut problem. Even a little better, a Lee collet die works well on the neck, then use a body sizing die. But, the best and easiest solution I found for myself is to simply seat the bullet so the bearing surface is above the donut.

Seating the bullet above the donut is the easiest and best method. If you have the throat to do so

Best die combo to mitigate donuts is a Lee collet/Redding body die combo

I’ve heard using the neck only Redding type s bushing die and Redding body die separately doesn’t create as much for donut issues. But I haven’t used that combo in anything but a 338 LM which I didn’t shoot enough to get donuts anyways.

I do know our fclass team (myself included) have all run into donut issues. Using sized up 6.5-284 Lapua brass (sized to 284) I had donuts on the second firing on the brass. Had bumped .002 on the shoulder with a fl Redding bushing die with .0015” neck tension. Went to seat with a forester seater and the seater would hang up on the neck of some. Thought I had a die issue. Sent the die to forester with sample brass and they indicated a donut was formed.

Those rounds were probably 25 out of 200 which chambered hard. I separated them pre match and used as first fouling shots as they weren’t consistent in velocity. They shot higher or lower as well. By about 3/4 moa from the rest

Think I may just get Lee collet die made for my 284 and run the collet/body die combo

 

[Nanook4311]

Thanks for all the help. I bought the K&M neck tension mandrel with .0025” tension, I am loading up hunting cartridges and that seems to be a nice compromise of tension. I am running Berger VLD’s just touching the lands, so I can’t seat the bullet out any further. I guess I’ll just try to minimize the formation and ream them out when they form. Any suggestions on doughnut removal. I am looking at K&M carbide cutter pilots. Anyone use these and if so can they be used every time I trim necks or should I move to a regular pilot? I also have a L.E. Wilson case trimmer, so I can get the reamer for it too

 

[whatsupdoc]

I would call or email K&M and ask them how to use the carbide cutter pilots.

According to K&M
"this tool will remove the excess material without affecting the inside neck diameter"

It may be similar to a method I sometimes use where I expand the case neck using a mandrel (that I have modified) to the exact size of the reamer and cut the doughnut with the RCBS tool. It works OK but not great.