How do you eliminate runout

Brett Bracken

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Jun 21, 2018
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64
Location
Midland, TX
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?
 

Trnelson

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Feb 15, 2012
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690
Location
Nebraska
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.
 

Savage 12BVSS

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Dec 20, 2019
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Maine
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!
 
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Brett Bracken

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Jun 21, 2018
Messages
64
Location
Midland, TX
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😡
 

jdyoung

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Joined
Mar 1, 2020
Messages
167
Location
Ironman Country
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

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Joined
Dec 6, 2012
Messages
699
Location
TEXAS
what is your measurement on the neck of a loaded round and what bushing size are you using
 

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