Neck sizing/Forster Die/Runout
- Thread starter Stud Duck
- Start date
I get the least neck runout with Forster full length dies using their expander.
I get more neck runout with neck sizing dies, and I believe this is due to the case body not being supported and held in alignment with the neck.
At the Whidden custom die website they tell you the get the most concentric cases with non-bushing full length dies. And Whidden does not make neck sizing dies.
NOTE, if you are measuring case neck runout after sizing with a expander the runout you see can be caused by neck thickness variations. I check my case necks with the Redding neck thickness gauge below and subtract these variations from the total neck runout readings.
Right now I'm sizing some bulk once fired Lake City 7.62 cases with a cheap Lee FL die and getting less than .002 neck runout. One of the biggest causes of neck runout is if the expander is locked down off center. And the Lee dies expanders are held and centered by the locking collet.
The only reason I'm using the Lee die is these once fired cases have badly dinged up case mouths. And the Lee expander straightens the necks out before the case are sized.
Below my Redding 243 FL die fitted with a modified Forster expander and spindle assembly. This modification greatly reduced neck runout vs the Redding expander on the left.
Bottom line you can take any full length die and remove the expander and the sized case will be as concentric as it ever will be. It is the expander and neck thickness variations that can cause most of the runout problems.
And at the Redding website they tell you to use the expander with their bushing dies if the cases have .002 or more neck thickness variations.
I get more neck runout with neck sizing dies, and I believe this is due to the case body not being supported and held in alignment with the neck.
At the Whidden custom die website they tell you the get the most concentric cases with non-bushing full length dies. And Whidden does not make neck sizing dies.
NOTE, if you are measuring case neck runout after sizing with a expander the runout you see can be caused by neck thickness variations. I check my case necks with the Redding neck thickness gauge below and subtract these variations from the total neck runout readings.
Right now I'm sizing some bulk once fired Lake City 7.62 cases with a cheap Lee FL die and getting less than .002 neck runout. One of the biggest causes of neck runout is if the expander is locked down off center. And the Lee dies expanders are held and centered by the locking collet.
The only reason I'm using the Lee die is these once fired cases have badly dinged up case mouths. And the Lee expander straightens the necks out before the case are sized.
Below my Redding 243 FL die fitted with a modified Forster expander and spindle assembly. This modification greatly reduced neck runout vs the Redding expander on the left.
Bottom line you can take any full length die and remove the expander and the sized case will be as concentric as it ever will be. It is the expander and neck thickness variations that can cause most of the runout problems.
And at the Redding website they tell you to use the expander with their bushing dies if the cases have .002 or more neck thickness variations.
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cw308
The Forster expander and spindle assembly fits on RCBS dies. The high mounted floating Forster expander enters the case neck when the case neck is held and centered in the neck of the die.
Below the RCBS expander on the left is raised as high as it will move. Some RCBS dies have the spindle threaded further down and can be raised as high as the Forster expander. And all you need to do is put a rubber o-ring under the lock nut and allow the expander to float.
The Forster expander and spindle assembly fits on RCBS dies. The high mounted floating Forster expander enters the case neck when the case neck is held and centered in the neck of the die.
Below the RCBS expander on the left is raised as high as it will move. Some RCBS dies have the spindle threaded further down and can be raised as high as the Forster expander. And all you need to do is put a rubber o-ring under the lock nut and allow the expander to float.
cw308
The Forster expander and spindle assembly fits on RCBS dies. The high mounted floating Forster expander enters the case neck when the case neck is held and centered in the neck of the die.
Below the RCBS expander on the left is raised as high as it will move. Some RCBS dies have the spindle threaded further down and can be raised as high as the Forster expander. And all you need to do is put a rubber o-ring under the lock nut and allow the expander to float.
I have been using an O ring to float expander stems wherever possible for many years now.
It works.
It works.
Dusty Stevens
Shiner
Not many on an accurate shooter website can tell you how much runout they get with a neck sizer.
Liven The Dream
Gold $$ Contributor
Well here is a story!
My .308 Redding Bushing Die with floater ball FL. Is a what if ?? Run out from .003 to .008 .
If I run that Brass back thru my Old very old RCBS SB Die with Hornady Floater Ball the run out is .001 to .003 ??
Then back to neck sizing .
I live with .0015 to .003
My .308 Redding Bushing Die with floater ball FL. Is a what if ?? Run out from .003 to .008 .
If I run that Brass back thru my Old very old RCBS SB Die with Hornady Floater Ball the run out is .001 to .003 ??
Then back to neck sizing .
I live with .0015 to .003
cw308
The Forster expander and spindle assembly fits on RCBS dies. The high mounted floating Forster expander enters the case neck when the case neck is held and centered in the neck of the die.
Below the RCBS expander on the left is raised as high as it will move. Some RCBS dies have the spindle threaded further down and can be raised as high as the Forster expander. And all you need to do is put a rubber o-ring under the lock nut and allow the expander to float.
After reading this post and the material in the McPherson book about modifying RCBS spindles to move the expander ball higher, I've decided it's an improvement I'd like to try. Not sure why McPherson does so much machining if the Foster part is a drop-in for not much money. I think he reduces the diameter of the spindle on a lathe and then re-threads it. I don't have a lathe or the right die, so I'm not going to do that. I'm wondering, if I replace the spindles in my RCBS FL resizing dies with Forster's, will they control runout as well as a Forster FL die, or should I shelve the RCBS dies and just buy Forster FL dies?
Don't know, the answer to your question, (and didn't want to waste my Time, on trying, this "option" ) BUT,..
Got rid of, ALL my RCBS SIZER Dies and went, ALL Forster Sizers ! TIR of, .002 Max with, EVERY, Die / Cal. that, I own AND, my Groups, shrank ! I even bought some used ones off, E-Bay ! Life's too Short, to have BAD, Bullet, "run out" !
Got rid of, ALL my RCBS SIZER Dies and went, ALL Forster Sizers ! TIR of, .002 Max with, EVERY, Die / Cal. that, I own AND, my Groups, shrank ! I even bought some used ones off, E-Bay ! Life's too Short, to have BAD, Bullet, "run out" !
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I can’t answer your question directly either, but I have put the Forster stems in several Redding and Rcbs FL dies and it does make sizing smooth and easy. Just got through loading a bunch of 22-250 PPU brass on the converted rcbs die, and the neck tension on the bullet was .001 for a reference.
When sizing, I use, a TINY bit of, Hornady Unique Lube, on, a Nylon Brush pushed back / forth 3-4 times in the Case Necks, THEN,. swab them clean / dry with, a Q-Tip, afterward.
Loosen the expanders lock nut and then wiggle the expander on any resizing die. After doing this you will understand with the sloppy threads how easy it is to lock the expander down off-center and induce neck runout.
If you let a standard expander float and if the case has dings in the rim the case can tilt on the down stroke of the ram and you still will induce neck runout. And the high mounted Forster expander enters the case neck when it is held and centered in the neck of the die. Meaning it does not pull the necks off center and induce runout.
You can take any make resizing die remove the expander and size a case and it will be as concentric as it ever will be. You can use an expander die to expand the necks and reduce neck runout. Or use a body die and a Lee collet die to reduce neck runout.
But with a Forster die and its high mounted floating expander you only need to size the case once to achieve the same results as sizing the case twice.
Forster makes the Co-Ax press that lets the dies float and self center. And the Forster dies allow the expander to float. So why argue with a good idea and concentric cases with very low to no runout.
NOTE, the reason so many reloaders use the Lee collet die is that it produces less neck runout than a bushing die. And smart, good looking and modest reloaders use Forster dies.
If you let a standard expander float and if the case has dings in the rim the case can tilt on the down stroke of the ram and you still will induce neck runout. And the high mounted Forster expander enters the case neck when it is held and centered in the neck of the die. Meaning it does not pull the necks off center and induce runout.
You can take any make resizing die remove the expander and size a case and it will be as concentric as it ever will be. You can use an expander die to expand the necks and reduce neck runout. Or use a body die and a Lee collet die to reduce neck runout.
But with a Forster die and its high mounted floating expander you only need to size the case once to achieve the same results as sizing the case twice.
Forster makes the Co-Ax press that lets the dies float and self center. And the Forster dies allow the expander to float. So why argue with a good idea and concentric cases with very low to no runout.
NOTE, the reason so many reloaders use the Lee collet die is that it produces less neck runout than a bushing die. And smart, good looking and modest reloaders use Forster dies.
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I agree. After much testing I will now ONLY buy Forster dies for any loads where I want precision. And FL dies, no neck sizing only. Don't get me wrong, I like Redding dies but results speak for themselves. Forster gives me the least runout, hands down.
I bought a carbide expander for my Redding .243 die and the expander was only .0001 smaller than bullet diameter. I guess Redding was hoping for a good bit of brass spring back and in an email they told me the expander was within manufacturing limits. How many of you reloaders use .0001 bullet grip when Redding tells use to use .001 to .003 bullet grip.
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