I recently purchased 300 new Win 30-06 cases for my '06 Ackley. I culled them via a Sinclair Mic-4 neck wall thickness gage http://www.sinclairintl.com/cgi-bin/category.cgi?catego...tem=MIC-4&type=store

I was able to cull out 55 cases which had a neck thickness variation of .00075" or less. When reading Glen Zediker's book on reloading he suggests neck turning only the best cases to get them as close to zero runout as possible. I'm dying to turn them but wonder if my chamber's neck to too generous to really make a difference. The case necks are averaging .0013" thick.

My fired case necks are running .341". Sized via my Lee Collet neck die they run .332". A .009" difference.

.308" bullet diameter
.026" neck thickness .013 x 2
.334" total

What do you think of these numbers and whether or not I should turn my necks?

Big Al,

First of all the .30-06 Ackley is one of, if not the finest cases designed.

I would turn the necks ONLY to clean up approximately 85% of the variation. Unless you have a "tight neck" custom chamber you can create more problems than you solve by turning necks.

I have a heavy barrel 25 WSSM that I have fallen in love with and turn necks just as I have recommended to you.

I second that. Unless you have a custom barrel on that rifle with a tight or match neck then you will really do nothing by turning them as your chamber will be larger anyway.

I have looked at the groupings both with neck turned and neck sized and in most cases, except for a couple of custom made rifles, no difference- in fact, neck sizing seems to be a tad better but it is so small a difference I cannot really say.
I can say that it does not markedly improved anything on most of my regular hunting rifles.
Even when it makes a difference in those with tight chambers, it is in the 1/10 inch range for 5 shots.
Doubtful most could tell anything.

quote:

Originally posted by GSSP:

I was able to cull out 55 cases which had a neck thickness variation of .00075" or less.

What brand and model of dial indicator is able to read 5/100,000 (or less) of an inch?

quote:

What brand and model of dial indicator is able to read 5/100,000 (or less) of an inch?

M1A1 Eyeball

quote:

Originally posted by onefunzr2:
[QUOTE]Originally posted by GSSP:

[quote]I was able to cull out 55 cases which had a neck thickness variation of .00075" or less.

quote:

What brand and model of dial indicator is able to read 5/100,000 (or less) of an inch?

The Sinclair rig mentioned uses a micrometer with graduations of .0001"

GSSP :

varmint Al has a good read on neck turning. When to when not to and how to.

http://www.varmintal.com

muck

quote:

Originally posted by muck:
The Sinclair rig mentioned uses a micrometer with graduations of .0001"
muck

You can probably use other dial indicators with this jig, but the ones Sinclair sells are graduated in .001".

- mike

mho

The rig I refered toi is the one that has a Sterret micrometer with a ball anvil, not a dial indicator. Sorry for any confusion

muck

Fair enough, the neck micrometer is indeed calibrated in .0001".

http://www.sinclairintl.com/cgi-bin/category.cgi?catego...tem=MIC-3&type=store

The device the original post related to was this:

http://www.sinclairintl.com/cgi-bin/category.cgi?catego...tem=MIC-4&type=store

- mike