How do you eliminate runout

[Brett Bracken]

In an effort to improve my reloading process with the intended goal of improving accuracy, SD and ES I have invested in a concentricity gauge to measure runout on my brass necks and finished loads. I also just started using a Redding type S full length "bushing" sizing die to control neck tension. For some darn reason all of my brass necks are ending up with about .0015"-.0025" of runout. What am I doing wrong?

 

[rsmithsr]

are you still pulling a button thru the neck of just bushing sizing ?

 

[Trnelson]

In an effort to improve my reloading process with the intended goal of improving accuracy, SD and ES I have invested in a concentricity gauge to measure runout on my brass necks and finished loads. I also just started using a Redding type S full length "bushing" sizing die to control neck tension. For some darn reason all of my brass necks are ending up with about .0015"-.0025" of runout. What am I doing wrong?

Could be a number of issues. 0.0015" is not a terrible reading, If that is total runout. May even be as simple as a set up issue in zeroing your concentricity gauge. I'd start there first. Next thing I would verify is the concentricity of your expander itself followed by how well it centers in the die itself. I used to measure runout, I do not any longer. I found that in my rifle it had no measurable effect on POI or precision out to twice my comfortable hunting range.

 

[cohunt]

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[JMW67]

if you are pulling the expander through have you tried skim turning your necks

 

[Brett Bracken]

In an answer to all the above....I have turned all the necks and have removed the expander ball/depriming pin from the die.

 

[Savage 12BVSS]

Concentricity is a pet subject of mine, spent a long time getting a handle on it and find it to be ignored or sought after among accuracy shooters. It takes an accurate rifle to really show its effect and it won't make up for limitations of rifle or shooter.

First thing to do and you have the equipment to check it, is fire some rounds in your rifle and check this fired brass for neck runout. I prefer once fired brass for this and write down what your rifle chamber produces in neck runout. Thats your starting point, now resize some of this brass with your chosen die. This is where it gets tricky.....what die do you use and are you going to neck size or bump the shoulder, or full length resize? I've been down this road and the neck runout you measure should lead you to the best set-up for your shooting. I reload brass 3 times and then full length shoulder bump, then three more loadings to next shoulder bump. I use a lee collet neck die for the between bump loadings and a forster benchrest FL die with expander and spindle removed for the bump loadings. I get a dozen or more loadings from quality brass (lapua and norma) so thats about primer pocket life. Here is what I've experienced at this point, my lee collet neck mandrel die produces .0005 neck runout when set up 1 1/4-1 1/2 turns after touching shellholder. THIS IS NOT what lee suggests as a starting point in their die instructions. A search on lee collet neck die adjustment will bring up a detailed way to do it by J Valentine from 2008 on a benchrest forum. This is the way to adjust it trust me. Now if I can replicate the neck runout from the chamber after bump or neck sizing by using the collet die in either case as the final sizing step, then where I fight runout is in the seating step.

I use the forster benchrest seaters with the sleeve, I turn the cartridge twice during the seating stroke and then measure final runout on the finished cartridge. Out of 40 loads on average about 15 will, on average, exceed .001.......up to as much as .0015, these I will tweak down to .001 or less on a hornady concentricity gauge. The remaining 25 will run between .0003 and .001. There are collet supported mandrels and straight mandrels as well as bushing dies, all improve runout over pulling a resizer button thru the neck. For me .001 or less is the number I look for Good Shooting!

 

[Brett Bracken]

Thanks Savage.....I am doing pretty much everything you're are saying and with the same equipment except for the Lee collet die. My fired brass has anywhere from .0005-.0010 runout to start with. I run my brass through a universal decapping die first then I throw them in a tumbler and clean them. Next, after cleaning, I anneal all the necks. Then I run them through my Redding bushing die w/o the expander and decapping pin....3 strokes( rotating the brass 1/3 rotation each stroke). Then I seat the bullets with a Forster Ultra Micrometer seating die. Still getting .0025" runout

 

[Brett Bracken]

I forgot to mention that I am full length resizing with .001" shoulder bump.

 

[cohunt]

Have you tried just sizing the next 1x? Not sure it will change anything but it's something to check

 

[jdyoung]

Thanks Savage.....I am doing pretty much everything you're are saying and with the same equipment except for the Lee collet die. My fired brass has anywhere from .0005-.0010 runout to start with. I run my brass through a universal decapping die first then I throw them in a tumbler and clean them. Next, after cleaning, I anneal all the necks. Then I run them through my Redding bushing die w/o the expander and decapping pin....3 strokes( rotating the brass 1/3 rotation each stroke). Then I seat the bullets with a Forster Ultra Micrometer seating die. Still getting .0025" runout

When you run 'em through the bushing die, do you pause on each stroke and let the brass settle ?
I also like to partially seat the bullet , ease up just a skoosh, and then turn the case w/bullet for the next stroke. Three strokes per cartridge.

 

[JMW67]

what is the run out on a loaded round

 

[Brett Bracken]

jdyoung....when I resize I run the ram up and then lower it....I don't pause.
JMW67....runout on a loaded rnd is about .0025" measured on the bullet.

 

[JMW67]

what is your measurement on the neck of a loaded round and what bushing size are you using