How much of the neck do you bushing size?

[TackDriver284]

After swapping from 140 Berger Hybrids to 140 Nosler Ballistic Tips on my 6.5 Creed, I noticed a " donut feel " when seating the Ballistic Tips past the neck / shoulder junction with my Redding Type S bushing full size die. The Hybrids and 120 Ballistic Tips just stops short of that junction so I never felt that donut feel. The 140 Ballistic Tips have a very long bearing surface, so after I fired those rounds, groups were not bad at all ( posted those on my previous 6.5 Creed / Ballistic Tips thread ) and I was back on the bench doing some checking and adjustments.
I normally put the bushing numbers facing down, tighten the cap until it makes contact with the bushing, and back off a quarter turn and set it at that level so the bushing can float while sizing. This is a first donut feel for me, so I opened the die and cleaned everything up and reassembled it and backed off the bushing a full turn so that it sizes roughly 70% of the neck instead of 90-95% . I ran a .262 Sinclair mandrel ( .002" neck tension ), primed the brass and added the same charges as the previous test, then seated the Ballistic Tips,,,,boom, no more donut feel on any of the 15 pieces I sized. Brought a smile to my face that I eliminated that variable. Tested those charges again at the range and it seemed to make me smile even more. It's definitely more than ready for some deer or a red stag.

Not sure if that is extra brass flow coming from sizing and firing which pushes the brass flow up to the neck shoulder junction. I do anneal after every firing. If looking at the neck closely, you can see the little bulge above the neck / shoulder junction, that area is not sized after firing, and the neck / shoulder junction below that looks a little constricted than the rest of the neck. The shank of the bullet is way below the neck / shoulder junction as well.
Do you guys size the whole neck or partial with your bushing dies? Have you ever experienced that donut feel and your methods to eliminate it?

 

[Ralt71]

I set my bushings the same way, I don't think you are doing anything wrong or there is anything to adjust here. The only thing I would add is I use a mandrel on mine lastly and I do not have any issues with donut formation. I use bushing dies on all my loads except .223 and my daughters 7-08.

 

[jimbires]

Mark , I was going to start testing this , but life got in the way . I just love a new rabbit hole to go sniffing through . I have read there is only so much neck tension you can get by sizing the neck smaller . because the bullet acts like an expander mandrel . what I've read is the only way to adjust neck tension , is by the length of neck you resize . I'm not sure of what a minimum length of sized neck would be , obviously the max length is to the shoulder . I'm not sure what increments you would use to test this theory . I was going to move in 0.050" increments , starting from just above the donut area . if nothing showed up , I was going to go to 0.025" increments and run the test again . I'm not sure if this is to try and help, group size , SD / ES , or maybe just the shape of the group . I thought it was interesting and wanted to see if I could tell any on target changes . I'm the guy that sizes the neck about , 0.004" or 0.005" , then uses a mandrel to expand it , to get my 0.002" tension . according to what I've read , my 0.002" tension is really not tension , but it's actually the interference fit . "tension" will be adjusted by the length of neck that is sized . to do this , I was going to use the bushing only , no mandrel .


I do not size to the shoulder with my bushing dies , because of the chance of donuts . even though I use a mandrel last , you don't move donuts around that easy , you have to cut them out . yes these donuts are caused by brass flow .

 

[SJB358]

The only donuts I experience are from Making 300 Win in 7 Mashburn Super, since some of the Wins shoulder becomes neck in the forming process. I use a K&M inside neck reamer and hit them pretty heavily and haven’t ever had one come back. Other than that, very little experience with it.

Do FLS using my Redding Bushing dies though.

 

[Charlie-NY]

I had the same problem with 6.5PRC Lapua brass. Donuts formed quickly. I use Redding Type S FL bushing dies. I used a .2625 mandrel after sizing, which may have helped, but it did not resolve the problem. The easiest solution is to just shoot bullets that don't interfere with the donut.

 

[RL338]

I still use bushing dies on 3 cartridges 338 LM , 7-08 , and 25 Creed. All 3 are FL sizing dies and set neck tension with bushing , no expanding. Bushing numbers down and lightly loose in the die as you described , with no doughnuts.
I used to size the 30-378 Wby with a Redding neck bushing die , it was a doughnut maker. I switched to a Forester honed FL die and it stopped. I was thinking it was due to using a body die then the neck bushing die causing it.

 

[TackDriver284]

I still use bushing dies on 3 cartridges 338 LM , 7-08 , and 25 Creed. All 3 are FL sizing dies and set neck tension with bushing , no expanding. Bushing numbers down and lightly loose in the die as you described , with no doughnuts.
I used to size the 30-378 Wby with a Redding neck bushing die , it was a doughnut maker. I switched to a Forester honed FL die and it stopped. I was thinking it was due to using a body die then the neck bushing die causing it.

I have stopped using Redding neck bushing sizing dies long ago for this reason and I'm strictly a full size bushing guy.

 

[Ralt71]

I do not size to the shoulder with my bushing dies , because of the chance of donuts . even though I use a mandrel last , you don't move donuts around that easy , you have to cut them out . yes these donuts are caused by brass flow .

Is this donut formation you are speaking of only a product of excessive shoulder bump though? I do not have issues with donut formation in my brass. Some rifles my shoulder is only .001 and some is .002. I run a mandrel the full length of my neck and then some. My neck tension is either .0015 or .002. I full length size everything though. I don't use neck only dies on any of my cartridges, including the belted ones.

 

[jimbires]

Is this donut formation you are speaking of only a product of excessive shoulder bump though? I do not have issues with donut formation in my brass. Some rifles my shoulder is only .001 and some is .002. I run a mandrel the full length of my neck and then some. My neck tension is either .0015 or .002. I full length size everything though. I don't use neck only dies on any of my cartridges, including the belted ones.

we all know brass moves , or we would not have to trim our cases . donuts are formed from thicker shoulder brass moving into neck brass . how this happens , I'm not sure . repeated firing and sizing causing the brass to move , is my guess . I would say over working the brass would contribute to the problem . by this I mean, pushing the shoulder back more than is necessary during sizing . I have a wildcat cartridge that pushes the shoulder back , and puts this shoulder brass into a longer neck . it also necks the original brass down , from .308 - .284 . there are donuts when the case is pulled out of the forming die . very obvious donuts . after I get rid of the donuts , I don't have them return , not that I can tell anyways . .

forgot to mention ; some guys that thickness turn their necks , will allow the cutter to go against the brass case shoulder a lot . this thins the thicker shoulder brass to help prevent donuts . I'll look around for pics of this to show you . I'm short on time this morning .