Concentricity Gauges

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I'm in the market for a good Concentricity gauge. Any wisdom here? I would like to get one that does all measurements (neck walls, bullet and case) but don't want to sacrifice quality. Sinclair looks promising to me but does not look like you can measure neck walls.
 
There have been extended discussions about this subject on all the boards, the discussions getting pretty technical.

Basically, there are two types of gauges, which vary in use depending on how they hold the cartridge and measure it. Since the two different types measure in different ways, they give different results. I have both.

The first is the one by Hornady, which holds a cartridge by its base, then lets you correct runout.

The other is by Sinclair. It supports a cartridge case at two points, but doesn't let you correct excessive runout.

Both are supposed to do a good job of measuring runout, providing the case has no defects that might skew the results.

As to whether using such a gauge is needed to wring the last amount of accuracy out of a cartridge is hotly debated. I have no answer because I have not gotten around to running any tests. At some point I plan to do so, but it won't be any time soon.

I suppose if you are shooting a big cartridge in competition over a l-o-n-g-g-g distance (e.g. 1000+ yards), it might be worthwhile.
 
The Sinclair gauge does a good job when paired with a quality dial indicator. If you really want to step out there, get an Accuracy One concentricity gauge.
 
Sinclair looks promising to me but does not look like you can measure neck walls.
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You would be correct.

I've got a Sinclair gauge, and it does what I need it to do. I do wish there was a spring loaded "finger" that would hold it on the gauge though.

As far as it being a useful measurement, I don't use mine very often. Usually when setting up dies or changing bullets as a sanity check.

I shot a 1k match a few years ago and got really neurotic about the loading process. I used fireformed Lapua weight sorted brass, and at the end of the loading process sorted them again by bullet runout. They were as consistent and precise as I could get them for a semi-production gun.

My best group of the day was sub MOA (8 7/8") at that distance using a wood stocked Cooper and NF glass.

i-8tv7Sxq-M.jpg

Oddly enough, a few months ago I shot 1k at the same range while goofing around. Load was different, and they were assembled without the same precision, then stored in a 100 round box under a tarp outdoors for about 3 months (I was moving). I shot a 6" group that day.

I attribute it to being better at reading wind, but YMMV.

IMAG0337-L.jpg
 
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I modified my Sinclair so I can get the shoulder closer. I must measure from the shoulder, because when the firing pin pushes the case forward, the shoulder is what is going to center the case in the chamber.

You could save yourself some money, don't buy a concentricity gauges, and just stop using that great big SAAMI neck chamber and they that big expander ball entering the case and then that little tiny die neck resizing the case neck and then that big expander ball pulling through the neck, opening the inside diameter and bending the neck.

Because that is where 75% of the eccentricity measured by the gauge is going to come from.

Try something else:

Even a bushing die is better than that.

Get a FL sizer die with the neck honed out to .002" smaller than the neck of your loaded ammo.

Take out the sizer ball / decapping stem from your sizer die. Get a decapping die, they are cheap.

Get a Lee Collet Neck die.
 

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Sinclair looks promising to me but does not look like you can measure neck walls.
Click to expand...
Nope.

You need to get a ball micrometer and measure the neck wall thickness all around. As go the necks, go the body. If the necks are consistent, the body will be as well, and vice versa. You'll find the better brass is not only more consistent weight wise, but far more importantly, the thickness is much more consistent all the way around.
 

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I have a NECO. It works well. So do others though. There are more choices these days.

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