If your barrel, action, and bullets are not up to it, all that will be a waste of time.
If they are, it can sometimes help accuracy.
Neck turning is most often used for tight necked custom chambers. Other than that it is mostly a waste of time IMO. At the most take off enough so 3/4 or so of the neck has some brass removed. Getting too thin isn't good either.
Since it is .30-06, I am going to assume hunting. If it is, I would not waste my time neck sizing etc. I would partial full length size and call it good. That will usually shoot extremely well, or at least as well as the gun is capable of unless it is match grade.
With partial full length sizing your brass will last a long time. If you have turned the necks they will be getting worked even more to fill the chamber, and will often split sooner than if you left them alone. After all, we are looking to work the brass as little as possible when we partial full length size.
I wish I had marked a fairly recent thread where we discussed PFLS in great detail. The definition was also debated a bit. Very good thread.
Here is a thread that shows different ways to measure where the shoulder is so we can bump it a set amount.
http://www.thehighroad.org/showthread.php?p=6270171#post6270171
What I call partial full length sizing (PFLS) is this. We adjust our sizer so that we bump the shoulder a couple of thousandths. That way the brass is a tight fit in OUR chamber, reducing headspace which reduces case stretching just above the web, prolonging brass life.
When we fire a round at full pressure it expands the brass case to fit the chamber. The brass springs back a hair enabling us to eject it. (This is one of the qualities of brass that makes it ideal for the application.)
Now we have a brass case that we can use various tools to measure where the shoulder is. Understand that it is slightly smaller than the chamber now. Start sizing the case a little at a time and getting measurements off the shoulder with whatever tool you decide to use. At first as the brass body is squeezed smaller the shoulder will move forward. Eventually as we turn the sizer down a little more the inner shoulder of the die will contact the shoulder of the case and begin to push it back. Go slow or you will go too far. We want to bump the shoulder back .001 to .003 max.
If the round was a light load, the brass will not fit the chamber well and if we push the shoulder back from there it will be too much. We need brass from a good full power load to set up the sizer. I like to use a case that has seen at least two full load firings on it, to be sure it is fully formed to the chamber, minus the spring back of course.
You can go one step further by using a full length sizer that uses bushings instead of an expander plug. That will work the brass less at the neck and eliminates the expander, which is the biggest cause of necks that are not concentric after sizing.
Bushing size? Mic a loaded round and subtract .002. That bushing will be close, but I don't know anyone who has ever managed to buy just one bushing, cause the math doesn't always work. Besides, we always wonder if a little more or a little less neck tension will shoot better and buy more bushings anyway.
Let me beat Larry to it and plug his nice headspace gauge first.
http://www.larrywillis.com/
It measures where the shoulder is so we can measure how much we set the shoulder back, keeping headspace to a minimum. There are other tools out there as well, from fancy to simple.
AC
