Neck sizing/Forster Die/Runout

[Richard Coody]

For those of you so concerned with runout I have a question.

Have you ever sorted your rounds by runout and compared the groups with low runout.rounds and high runout rounds? Have you found a point in runout where it starts to show on your target.

You might be trying to solve a problem that doesn't exist. My experience is if you aren't shooting consistent groups of a quarter inch or less runout less than .004 doesn't make much difference. You can easily read .003 of runout.just.from variation in brass thickness. Lots of nuances in reloading more important than runout.

 

[PopCharlie]

I'm with Uncle Ed. I get the least runout using Forster F/L benchrest sizers. I use an expander ball that is .001 less than bullet diameter. I polish the expander balls also. I also find the "sweet spot" where the ball is exactly centered in relation to the die body. I then measure distance between the bottom of the die lock nut and the bottom of the expander ball and record it. So, if I have to replace the ball, I can find the sweet spot again. I also index mark the top of the decapping stem and the die body so I can realign them when needed. This setup produces cases that have less than .0005 runout on the necks. The needle barely wiggles.
I use an arbor press with Wilson dies to seat bullets. This setup produces ammo with runout on the ogive of less than .001. I will occasionally get a .002 or so.

Having said all this, I think, based on my experience, that if you jump bullets, runout can affect accuracy. If you jamb bullets, runout doesn't matter. I have found that in my rifles, runout of less than .003 measured on the ogive of the round, is best for consistent accuracy. As we all know, there are other things that affect accuracy, like neck tension, seating depth, etc. Since I usually jump bullets, I treat runout with the same importance as neck tension or seating depth.

PopCharlie

 

[Sandstorm]

PopCharlie says;;:As we all know, there are other things that affect accuracy, like neck tension, seating depth, etc. Since I usually jump bullets, I treat runout with the same importance as neck tension or seating depth.

Im in agreement here as well...( Not many here neck size only anyhow )

 

[Iowa Fox]

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?

I give McPherson credit for screwing up the Lee collet neck sizing die. I remember all his Varmint Hunter articles where he was always reinventing the wheel.

 

[Uncle Ed]

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?

Some RCBS dies have a spindle threaded further down and can be raised as high as the Forster expanders.

The RCBS .223 expander on the left is not threaded as far and could not be raised as far as the Forster on the right. If the RCBS spindle is threaded further down then you will also need to put a rubber o-ring under the spindle lock nut and allow it to float.

I just used the Forster expander and spindle assembly because the Forster expander is much smoother than an RCBS expander. Below a closeup macro photo of a RCBS expander and gives new meaning to being in the rough.

 

[Richard Coody]

PopCharlie says;;:As we all know, there are other things that affect accuracy, like neck tension, seating depth, etc. Since I usually jump bullets, I treat runout with the same importance as neck tension or seating depth.

Im in agreement here as well...( Not many here neck size only anyhow )

I learned a lot going through the runout phase of my learning process. Once I got brass prep and what sizing and seating dies and procedure gave me the least runout my 21st century concentricity gauge gathers dust on the shelf. Now I do start the process below over with a new rifle/cartridge.

The gauge will let you know where in the process runout is being introduced.

Check runout on newly fired brass. That is the best it will ever be. All the imperfections in the neck are pushed to the inside.

Check runout after sizing. If that is where runout is being introduced there are lots of possible causes. Work through the possibilities and eliminate it.

Check runout after seating. Is this process inducing runout?

Once you get the process dialed in runout will be a thing of the past.

But again if your rifle doesn't show the difference on target is it really worth all that work? You decide.

 

[DrSteve]

Thanks to everyone that replied to my question. I learned a lot.