I need some advice from the experts. I have been checking 7 rm cases and some come up with some .004/.005 in. neck case runout.

I hjave neck turned them in a forster hand neck turning tool, and once I put them in the forster tool again, runout stays the same in spite of the fact that some brass has been eliminated.

Are yu talking about 0,1-0,12mm ? Seems good for me.
Why are you neckturning them, are you shooting competition?

Kimmo

Is this after firing or running them through your sizer?

Do you size the necks before turning? Do you have a neck sizing die or full length?Try to measure the neck after sizing and then again after shooting the case. Try sizing without the expansion collet on your depriming rod or deprime with the rod a little loose. When you have a case that has some runout I always make one very lite cut first and it it needs more than I make a second cut that cuts down on the heat on the brass which can gaul the inside of the neck when making just one cut to size. Imperial sizing wax is a great lube on the cases both inside the neck and outside the case. Good Luck

Try an experiment. When sizing the case run the case 1/2 way into the die, back off, rotate the case 90 to 180 degrees, finish sizing, back off a bit rotate case again pushing case into the die, slowly draw expander ball thru the neck.
There maybe be some slop in the die, shell holder, press that accumulate in the final read out in case accuracy.
Try it a couple if there's no effect you're out nothing.
Jim

If you do not size the necks first and then expand them on a mandrel to achieve a thigt fit on the neck turning mandrel you will not get consistent results. If the case neck to mandrel fit is sloppy you are much better of not turning the necks at all.

I turn my 7RM necks because of a thigt chamber (and because I reform from .300 WM), but the cases I use (Winchester and Norma) do not have enough variance to warrant turning for accuracy.

Tron

thanks for the info. I will try with the new ideas.

I resize in a neck sizer die before I ckeck runout.

A full length sizer will not produce RO, and will eliminate it, a neck sizer often will induce RO or make it worse if it exists. The only way to correct it is to FL size them. Sizing the neck without supporting and centering the body in the neck sizer is the problem that isn't associated with FL sizing.

�lg--Runout is frequently a problem associated with using dies that have the standard type internal neck expanding ball or button. It does not seem to matter if they are full-length or neck-only. You can virtually eliminate this problem by using Redding dies with the neck sizing ring and tossing the included neck-sizing button and buying an assortment of rings to cover you needs size-wise.

If, on the outside chance, you are talking about neck thickness run-out, then neck turning is the answer. Either that or purchasing Norma or Lapua brass in the first place.

New cases will have about that much run out even if you turn the necks. Once they have been fired in a good chamber they will be more true.

Turning necks is not for runout, but for thickness variation.

To get rid of the runout, get rid of the expander ball [big improvement], and [small improvment] buy a sliding sleve Forster or Redding seating die, or a Wilson seating die.

If you have .007" of thickness variation, switch brands of brass.

Is that neck or bullet runout? If it's neck runout it's borderline too much. The trick is not to neck turn which will drive you nuts in the long run but to select brass with even wall thickness and then work it just enough to hold the bullet but not so much as to induce more variations.

Turning necks will have no effect on "run out". Necks are turned to give a uniform thickness. I would expect the run out to be the same before and after turning. That just means you have removed same amount of metal all the way around. which means your necks were pretty well uniform in thickness to start with. Run out if a die (sizing or seating) problem or even a crooked chamber. Yep..not all chambers are dead straight.

is the sinclair hand tool set decent for outside neck turning?

I �ve been using remington and winchester brass. I will try with lapua/ norma.

Neck sizer die is a Forster; sitting die is rcbs competition.

The cmaber seems to be OK, I�ve checked fired rounds and neck RO is 0,001.

It is just some of the brass that does seem not to be straight.

I�ll try the scandinavians.

I dont have much dedicated equipment for case measurment, so I measured diameter of 2 loaded ammo examples.

Bullets dia about .3084"
Neck OD, max .3328, min .3322 --> one had .0004 and the other had .0005 spread between max and min for the 2 opposite case walls (.0120 wall thickness)

Fired case, neck OD .3400 --> .0075 expansion

Is this a candidate for requiring neck turning?

[ 10-23-2003, 21:45: Message edited by: bajabill ]