Runout problem with factory spec chamer

[ALR]

Hi Guys,

Can necking down from 0.340" to 0.332" with a Redding Type-S bushing die cause runout? My fired cases measures 0.340 and when I neck my turned (0.013") lapua brass to 0.332" the runout on the case necks are not good at all. About 0.003" to 0.006".

Will sizing incrementally produce better runout? I want at least 0.002" or better.

Any help will be appreciated.

 

[No1]

I'm going to go out on a limb and assume that you did not turn .013" off the necks, but you sized them down that much. (edit: I see now you were explaining you had previously turned the necks.)

Do not use the expander button with the neck bushing die. Your report back should be <.001 runout. The occasional piece of brass will be greater.
How did you arrive at using the .332" bushing? Measure the neck of a loaded round (average several) and subtract .002", that is the bushing you should use.

 

[ALR]

Hi No1, I did remove the expander. Got my bushing size by subtracting 0.002" from (the calibre (0.308") + 2 X neck thickness (2 X 0.013")), which gave me 0.332"

Just tried going from 0.340" to 0.334" and then lastly 0.332". These are the only two bushings I have available currently. The funny thing is that if I go to 0.334", the runout is always 0.002" or better, but the last bit to 0.332" distorts the cases randomly, and I get anything from 0.0015" to 0.004". I'll keep on trying. Maybe its my neck turning procedure, dunno. I'm also starting to suspect my 0.332" bushing's concentricity. Its a titanium nitrate one.

 

[No1]

Do you have the bushing where it floats a little bit in the die?
Fixed die or bushing die, I always lock the die down with a fresh case inserted. They only way I know to make sure that the whole die locks down as straight as possible.
What press?

 

[ALR]

Yes I made sure the die was set up as good as I know how, with the die touching the shell holder, 1/16" turn back on the decapping rod to allow self centering of the bushing, expander removed, imperial sizing wax used etc.

Will try locking the die die with case inserted and see what it does. Press is a RCBS Reloader Special - 5. It still doesn't make sense why the 0.334" bushing produces good runout, and thats a normal steel one too. I will confirm this and get back.

What can I do to determine the integrity of my press? Use a FL die on new brass without expander or what?

I really need to eliminate the weak links in my process. Accuracy is not terrible for a factory rifle, looking at 0.5-0.8MOA for five shots at medium ranges (200yd-600yd), but I need to improve.

 

[QuietShootr]

Why so much neck tension? If things are working well with .334, why not go with that? You still have way more than I use, and my bullets don't move.

 

[Rob01]

What is the measurment of the outside of the neck with a bullet seated? That's how I get my determination for bushing to be used. Measure the outside and subtract .002".

Also when I need to neck size down I do a step down at no more than .005" at a time as is recommended by Redding.

 

[ALR]

QuietShootr, because I decided on 0.013" neck thickness and have already turned half my brass.

0.334" will give my theoretically zero neck tension.

Maybe there is some kind of threshold where if you decrease the diameter past a certain point with a specific neck thickness it creates internal forces that causes runout. Maybe anneal every second time before I size?

 

[ALR]

Thanks Rob01

 

[QuietShootr]

Yup, this.

What is the measurment of the outside of the neck with a bullet seated? That's how I get my determination for bushing to be used. Measure the outside and subtract .002".

Also when I need to neck size down I do a step down at no more than .005" at a time as is recommended by Redding.

 

[Rob01]

No problem. Glad to help when I can.

Forgot to ask but why are you turning the necks? With the fired .340 number you gave I am guessing it is a tight neck chamber as most .308s come out about .343-.345. Where the loaded rounds too tight in the chamber so you decided to turn?

 

[damoncali]

What is the runout on a fired case neck before sizing?

 

[ALR]

Rob, I decided to turn necks in order to achieve a low ES (shooting out to 1000yds lately), theoretically at least. Plus my Lapua cases turned to 0.013" is thicker than unturned Norma brass that I used to have.

Runout on fired cases vary between 0.0005" and 0.001".

There is maybe one more thing. Feel a bit silly to confess, but I could not achieve a perfectly uniform thickness on the necks when using the Forster NT tool. Variance on the neck wall thickness was about 0.4thou max. Cant think thats the issue.


Sent from my iPhone using Tapatalk

 

[damoncali]

I'd put my money on sizing too much at once. But you should be able to get better consistency out of your neck turner than .0004" - it should be closer to .0001".

 

[Rob01]

Honestly I would say stop neck turning. I have never turned a neck and shoot just fine to 1000+. Sounds like you are doing more harm than good with the whole process and making your reloading more difficult and time consuming.

 

[ALR]

Thanks for the advice guys.

 

[damoncali]

Honestly I would say stop neck turning. I have never turned a neck and shoot just fine to 1000+. Sounds like you are doing more harm than good with the whole process and making your reloading more difficult and time consuming.

I would agree with this. Neck turning has it's place, but not with factory chambers. It's more suited to very tight necked target rifles (benchrest, basically).

 

[No1]

Yes I made sure the die was set up as good as I know how, with the die touching the shell holder, 1/16" turn back on the decapping rod to allow self centering of the bushing, expander removed, imperial sizing wax used etc.

Will try locking the die die with case inserted and see what it does. Press is a RCBS Reloader Special - 5. It still doesn't make sense why the 0.334" bushing produces good runout, and thats a normal steel one too. I will confirm this and get back.

What can I do to determine the integrity of my press? Use a FL die on new brass without expander or what?

I really need to eliminate the weak links in my process. Accuracy is not terrible for a factory rifle, looking at 0.5-0.8MOA for five shots at medium ranges (200yd-600yd), but I need to improve.

I have an RS-5 press too. Something on it is severely misaligned. To get decent ammo I have to shim .015" on one side of my dies to get things straight. Now the RS-5 is only used for loading anything I don't have 550B conversions for.
Just saying that's a problem that exists with my RS5.

Using a FL die, no expander, on unturned fired brass will help determine if things are straight. Measure the runout before then after sizing.
It was my seating operation that first tipped me off to my RS-5 problems. Bullets would drag heavy on one side. Back tracking from there led me to the size die where I figured out how to shim and lock it down properly.

 

[SPAK]

Couple things... For a .340" neck you shouldn't have to neck turn to .013" neck thickness.. .014-.0145" is fine. You just want to clean up the neck for a no turn chamber.

Sizing down more than .005" at a time will induce runout like rob said.

if you're holding the neck turner too tight and not letting it "float" you will cause the cutter to cut uneven and this will induce runout and uneven neck thickness even though you're turning the neck.

Make sure you're adding lube to the turning mandrel.

if you're really serious about it, sort your brass by neck thickness variance before you turn. Lapua will generally be very consistent and have little variation case to case bit there are a few that would need to be culled, but not very many.

for my .340" necks using Lapua brass I turn for a slight clean up to .0140" size with a .3330" honed neck die for a finished neck of .3340-.3345". This gives me a loaded neck of .3360" and .001-.0015" neck tension which is more than enough.

i don't have to turn my necks but I do because it makes me feel better that I have consistent neck tension (or as much as I can get to consistent neck tension). It's definitely not a necessary step in my case.