Case Neck Thickness Variation

[bill123]

I know this has been touched on in many threads but I can't seen to find an answer that directly relates to my question:

I'm sorting brass by neck variation to get more consistent groups for 1000 yard. I'm trying to avoid turning. What is tolerable inconsistency in a neck?

My Lapua 308 brass runs from .0145" -.017".
50% of it is .015"-.016" within a case.
I have some running .015"-.0155" and some .0155"-.016.
There are very few cases that run .0145"-.015" or .016"-.017".

Any suggestions?

 

[Mikecr]

You didn't say your chamber neck diameter.
Personally, I cull anything outside .0005 total variance around necks, and covering desired thickness(whether turning or not). I do this to reduce runout down the road, and to ensure I'm not overworking necks in sizing, and to match my brass in H20 capacity.

Your variance spread is higher than normal though.
What are you measuring with?

 

[bill123]

You didn't say your chamber neck diameter.
Personally, I cull anything outside .0005 total variance around necks, and covering desired thickness(whether turning or not). I do this to reduce runout down the road, and to ensure I'm not overworking necks in sizing, and to match my brass in H20 capacity.

Your variance spread is higher than normal though.
What are you measuring with?

Fired case: .340"-.341"
Finished Lapua cartridge w/ bullet: .337"-.338"
Using a Redding Case Neck Gauge. There is a bit of slop in it.

 

[Mikecr]

Using a Redding Case Neck Gauge.

This is why you're getting so much variance..
You need a neck micrometer with a stop.

 

[bill123]

This is why you're getting so much variance..
You need a neck micrometer with a stop.

When I say slop I'm talking maybe 1-2 ten thousandths. What is the Redding tool used for?

 

[Deleted member 46119]

Turn em all to .0145

 

[bill123]

Turn em all to .0145

I was hoping to avoid turning by sorting and shooting like batches. Anyone use that strategy?

 

[Canadian Bushman]

Turn em all to .0145

Thats what i would do

 

[bill123]

Turn em all to .0145

About how long would it take you to turn 200 cases from say .0165" to .0145"?

 

[Canadian Bushman]

I turned, trimmed, and chamfered 300 lapua cases in about 4 hours not too long ago.

 

[bill123]

Personally, I cull anything outside .0005 total variance around necks, and covering desired thickness(whether turning or not). I do this to reduce runout down the road, and to ensure I'm not overworking necks in sizing, and to match my brass in H20 capacity.

Assuming you would have the desired thickness left, would you turn cases with only .0005" variance?

 

[flashhole]

If you are tooling up to turn them, turn all of them.

 

[jrock]

I sat on the sideline trying just what you are doing and eventually tooled up for neck turning. I also have a Redding neck thickness gauge but I ordered a 0.0005" dial gauge for it and get all my cases under 0.0005". If you want to be serious about it, I would recommend a micrometer. I shoot factor chambers and neck turning makes a difference in my guns. Once you get everything set up, it isn't as bad as everyone makes it out to be.

 

[bill123]

I sat on the sideline trying just what you are doing and eventually tooled up for neck turning. I also have a Redding neck thickness gauge but I ordered a 0.0005" dial gauge for it and get all my cases under 0.0005". If you want to be serious about it, I would recommend a micrometer. I shoot factor chambers and neck turning makes a difference in my guns. Once you get everything set up, it isn't as bad as everyone makes it out to be.

What's the dial gauge for the redding tool?