Is this common (bushing die step size)

stump shooter · December 21, 2009, 03:09 PM

My .308 case necks (Winchester brass) measure at the top end of specs of .3435" fired dia. I am full length sizing with a Redding F/L S bushing die and bumping the shoulder .0015"-.002".

What I have found is that in order to get my neck down onto a bullet for .002" tension I can use the .332" bushing...a decrease of .0115 from fired measurement. It will hold the bullet correctly, but it leaves a visibly flared mouth after leaving the bushing. I expect this is a result of too much sizing at once.
I did some researched and found that it is advised to not size more than .010" at one time to avoid overworking the brass (regarding case reforming), so I decided to try something different: step the neck down half way with a .338" bushing, and then run the neck through the .332" bushing to achieve proper bullet fit. Now my necks are perfectly straight and uniform with proper fit! Trim, load and go...little groups, big smile

I am also wondering if I have this much neck work occuring do I need to be extra vigilant with annealing?

I am assuming that squeezing the neck down on only one pass is really overworking the brass and would create more problems sooner. Does my revised method have the right madness to it?

**Unclenick** · December 21, 2009, 06:26 PM

Sounds like some spring-back when you resize in one shot. I've not encountered that, but it apparently your cure works. I think your notion to anneal more frequently is correct. Indeed, you may find a newly annealed neck can be successfully resized in one step? No question that extra expanding and sizing will work harden the brass faster.

Watch out for the formation of the "dreaded donut". This is where brass flows into the junction of the shoulder and neck. If you seat bullets with bearing surfaces long enough to reach that spot, the donut can pinch them, causing excess pressure. They need an inside reamer to clear. One of the things I've come to like about the inexpensive Lee Collet Die is it inherently prevents the donut from forming. It also requires frequent annealing, though, to work smoothly.

stump shooter · December 21, 2009, 07:20 PM

LOL, a buddy who does a lot of vaminting said the same thing, "if it works, stay with it"

I was also told that due to my fired neck dimension/chamber tolerance and the WW brass typically being thinner, it's not a surprise that I'm having to size them down so significantly to achieve proper bullet fit.

BTW, if anyone is wondering, the expander ball is removed for fired cases.
I only use it on virgin cases to iron things out; and speaking of this, Thanks for the mention on the Lee Collet die Unclenick, I may pick one up just for my new brass prep in the future. It didn't occur to me until now how much it might benefit new cases and true them for the the first loading. ( I suppose Mr. Lee put that part in the book for a reason

)

December 21, 2009, 03:09 PM	#1
stump shooter Member Join Date: March 23, 2008 Posts: 61	Is this common (bushing die step size) My .308 case necks (Winchester brass) measure at the top end of specs of .3435" fired dia. I am full length sizing with a Redding F/L S bushing die and bumping the shoulder .0015"-.002". What I have found is that in order to get my neck down onto a bullet for .002" tension I can use the .332" bushing...a decrease of .0115 from fired measurement. It will hold the bullet correctly, but it leaves a visibly flared mouth after leaving the bushing. I expect this is a result of too much sizing at once. I did some researched and found that it is advised to not size more than .010" at one time to avoid overworking the brass (regarding case reforming), so I decided to try something different: step the neck down half way with a .338" bushing, and then run the neck through the .332" bushing to achieve proper bullet fit. Now my necks are perfectly straight and uniform with proper fit! Trim, load and go...little groups, big smile I am also wondering if I have this much neck work occuring do I need to be extra vigilant with annealing? I am assuming that squeezing the neck down on only one pass is really overworking the brass and would create more problems sooner. Does my revised method have the right madness to it?

December 21, 2009, 06:26 PM	#2
Unclenick Staff Join Date: March 4, 2005 Location: Ohio Posts: 21,743	Sounds like some spring-back when you resize in one shot. I've not encountered that, but it apparently your cure works. I think your notion to anneal more frequently is correct. Indeed, you may find a newly annealed neck can be successfully resized in one step? No question that extra expanding and sizing will work harden the brass faster. Watch out for the formation of the "dreaded donut". This is where brass flows into the junction of the shoulder and neck. If you seat bullets with bearing surfaces long enough to reach that spot, the donut can pinch them, causing excess pressure. They need an inside reamer to clear. One of the things I've come to like about the inexpensive Lee Collet Die is it inherently prevents the donut from forming. It also requires frequent annealing, though, to work smoothly. __________________ Gunsite Orange Hat Family Member CMP Certified GSM Master Instructor NRA Certified Rifle Instructor NRA Benefactor Member and Golden Eagle

December 21, 2009, 07:20 PM	#3
stump shooter Member Join Date: March 23, 2008 Posts: 61	LOL, a buddy who does a lot of vaminting said the same thing, "if it works, stay with it" I was also told that due to my fired neck dimension/chamber tolerance and the WW brass typically being thinner, it's not a surprise that I'm having to size them down so significantly to achieve proper bullet fit. BTW, if anyone is wondering, the expander ball is removed for fired cases. I only use it on virgin cases to iron things out; and speaking of this, Thanks for the mention on the Lee Collet die Unclenick, I may pick one up just for my new brass prep in the future. It didn't occur to me until now how much it might benefit new cases and true them for the the first loading. ( I suppose Mr. Lee put that part in the book for a reason )