Neck sizer runout help!

nhassey48

Sergeant
Full Member
Minuteman
Mar 17, 2010
217
0
35
Arizona
My fire formed rounds have about .001 run out in them. Maybe a little less. Once I neck size them, it immedietely goes to .003 run out. How do I reduce this. Please help! My full length die makes it about .001 as well. It seems like all my neck sizers suck.
 
Re: Neck sizer runout help!

I've gotten away from the standard neck sizer dies and gone to bushing style dies that support and align the cartridge in an internal sliding sleeve as it is being raised into the bushing. I know that doesn't help at the moment so let me keep going a bit.

When using the standard neck die I would remove the sizing button as it is an oft claimed culprit of causing runout. Debris and film build up can cause runout so cleaning the die occasionally is important. Lastly, when using those dies, I had the best success making sure the neck was well lubed. Some guys use the powder (and I do too but just to see how far down the neck I am sizing) but I've had the best success with the sprays such as One Shot.

Now my dies are Redding competition s bushing with nitride bushings so I don't even have to lube anymore.

As an aside, I used to check runout obsessively, sort cases by runout, etc. I'm not so sure that was necessary at all. Good luck.
 
Re: Neck sizer runout help!

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: A.O.R.G.S-Hassey</div><div class="ubbcode-body">I am using a standard RCBS neck sizer. Sorry </div></div>

Bushing dies with the case fully supported before the bushing touches the neck.
 
Re: Neck sizer runout help!

rcbs neck dies suck , i tried 2 , 30-06 and 308 , both didnt produce better accuracy then the regular f/l die. I guess the only positive on the neck sizer die is it prolongs case life ? maybe..

but, i use bushing dies , they do a better job. I take it your using the regular neck sizer and not the bushing type neck sizer ?

.003 runout isnt so bad , i settle .005 runout , you can spend allot of time messing with runout and i feel runout is not the deciding factor for accuracy ,i spent allot of time getting .001-.002 runout , i didnt really see an improvement on group size.

whats more , you got to consider your measuring device , how good is it ? is it top of the line ?

i worry more about wind calls then runout.
 
Re: Neck sizer runout help!

" It seems like all my neck sizers suck." "rcbs neck dies suck , i tried 2 , 30-06 and 308 , both didnt produce better accuracy then the regular f/l die. I guess the only positive on the neck sizer die is it prolongs case life ?"

Facts frequently run counter to "conventional wisdom", don't it? Sorta suggesting the frequently touted info really isn't very wise? Perhaps nothing demostrates that better than neck sizing. Case life is rarely improved with neck sizing, as such, most cases fail due to neck splits and that will happen no matter if the body is sized or not. And most people do their neck sizing so poorly any potential accuracy advantage is usually lost.

No one can load straight ammo in crooked case necks. The 'best' neck sizer die for factory chambers seems to be the simple and low cost Lee Collet neck sizer; it gives the most concentric necks the caees are capabile of and leaves the "bullet tension" correct for minimum bullet run-out. But, the Lee die has a moving part, the collet itself, it's not a simple "push the case in, pull the case out" thing. So, those who have trouble with mechanical devices may do better with conventional - or bushing - neck dies.
 
Re: Neck sizer runout help!

If you don't turn your necks .002-3" of run-out can simply be the difference in case neck thickness from one side to the other.

Once you fire a case the neck forms to the ID of your chamber and any variation in neck thickness is inside the case neck but after sizing and pulling the expander ball through the neck the variation in neck wall thickness is now on the outside of the neck since the inside is now a set ID. So the difference your seeing after sizing could very well just be the difference is wall thickness.

I use Redding Type "S" FL Busing dies and see this a lot, I also thought it was the die until I turned the necks on a batch of brass and magically the run-out doesn't change after sizing.
 
Re: Neck sizer runout help!

Put an "O" ring between the lock nut on your decapping stem and the die body. That will let the expanding button free float a bit and better align with the neck. Try sizing without the button installed and see if the excess tolerance runout continues. If so, it is the die. If not it is the button.
 
Re: Neck sizer runout help!

I bet your neck die is sizing the brass down way too much in one shot, then the expander is jerking the neck back up and is inducing your run out
 
Re: Neck sizer runout help!

yea I turn my necks and with my FL die, I get less than .001. I guess I should take the neck sizer back and buy a Redding type S bushing die. Thanks
 
Re: Neck sizer runout help!

I quit using neck dies a long time ago when the perceived benifit was realized to be minimal at best.....

I'm a big fan of regular good quality FL dies set up to bump .001" at the shoulder, and of course turning necks.

I run my sizer die without the expander ball.

In another FL die I have a floating carbide expander kit installed way low and in a seperate step bump my necks up over the floating ball...expanding the necks on a short push-up-in stroke instead of pulling them down over.

This induces near zero runout in the sizing/expanding operation.

I've found that slatherassed bullet seating will induce far more runout than anything a quality sizing die can do to it.

Comp Seaters are golden.....
 
Re: Neck sizer runout help!

Ok, so I just bought a Redding type S neck sizer die set. I turn my necks to .013 thickness so I figured .248 and .249 bushings would suffice. Does anyone know whether or not those will work? Would appreciate the help! Thanks