Originally Posted by Moman
JE, with your permission, I would like to delve a little more into neck turning and how it may effect runout/concentricity. I think what I'm after will stay on topic.
How many of the posters up to this point neck turn their cases?
I ask because in the past I have settled for .001 neck wall variance and have been happy with that number. I have had trouble with this last lot of brass in that neck wall variance is anywhere from .001 to .005. The majority of the cases are .003. Runout on these loads it gynormous.
How much of a difference would it make if I were to neck turn these cases to .001 variance or less? How much would this help with runout?
You don't need my permission to bring up points of interest to this post. That's why I post
anything. to get different opinions.
I will give you my opinions on your questions and leave it at that.
First I will say that perfection may not be nessary because I do not know how to measure
the difference between a case that has .001 wall thickness and one that has .0005 so I just
try to make them as good as I can.
With my old neck turner .001 was about the best I could do ( And I did fine but wanted better)
so I bought a better neck turner (More precision and adjustable down to the 10 thousandths
and it did improve the consistency in neck thickness.
Next = the improvement in concentricity was phenomenal when I first turned the necks and then
sized the brass before fire forming the finished brass has almost no concentricity issues or
run out. All I can deduct from this is that with true neck thicknesses the neck is not pushed off by an uneven wall thickness and sizes more uniform , and when fire formed it is near perfect.
Again as I said I'm not sure how much difference it makes but it makes me feel better knowing
that I have the best ammo I can load. so that if an issue shows up I can look somewhere else
for the problem.
I do know that the more concentric the ammo is the better the groups and Standard deviations
So for precision shooting and testing ,I turn all of my necks in this way. Later I may decide on
some applications that the difference In a .100 thousandths group and a .250 is not worth
the effort but I know what the rifle is capabable of.
I hope you get a lot of responses !
Just My 2 cents
J E CUSTOM