Measuring Neck Wall Thickness

[Hunting 2019]

The Starrett ball measures 0.163

 

[Dos XX]

Mitutoyo Wall Thickness Micrometer with 60 Degree Modification

The Mitutoyo Wall Thickness Micrometer measures wall thickness of tubes, cartridges & cylinders. Our 60 degree modification allows you to take better measurements.

kmshooting.com

 

[dkhunt14]

Not trying to derail your thought, but I have had good luck and a lot less work making .22-250 from 6 and 6.5 Creedmoor brass. One pass in a standard FL die works for me. No neck turning needed with a standard chamber, only about .040 to trim off. I've made 150 in the last few months from once fired range pickup brass.

I have a Starrett ball micrometer for the times I do turn necks.

Anytime you neck down a case, the neck walls get .001 thicker. That means a seated bullet is .002 bigger. That could be a problem depending on clearance of chamber. Matt

 

[jimmymac]

I like my Sinclair micrometer.

 

[mikecr]

Danny, you're right. A pin anvil typically used in a 'tubing mic' won't work for our purpose, because our tube is tapered in shape and thickness (esp. with any donut). You would be measuring gaps.
For neck measure you need spot contact that a ball provides.

There are 2 other common flaws in what people are using even for ball neck mics:

1. They lack adjustable mouth stops. Cases vary in thickness from webs all the way to mouths. So if you're to see thickness and variance accurately, you need to set a datum of measure on necks. Will you measure 1/4 down necks,, 1/2 way, 3/4 down? Without a stop you'll be measuring all over the place and thickness will apparently vary on that alone.

2. They lack adjustable anvils. If you wish to creep into donut/neck-shoulder junction measure with a standard spindle, you only need an adjustable ball anvil. Tapering of the spindle does not remove remaining distance between anvil to spindle contact point (spindle center) to spindle edge.

Sinclair historically offered the best overall neck mics. But since Brownells bought them, Sinclair has lost or given up on some innovative products/suppliers. Their best ever neck mic is no longer sold, and their second best (the Starret with it's stand) hasn't been in stock for years it seems..
I couldn't suggest anything available today,, but you could build something.

 

[bobm]

Anytime you neck down a case, the neck walls get .001 thicker. That means a seated bullet is .002 bigger. That could be a problem depending on clearance of chamber. Matt

With respect for the OP, I'll post my findings about your comments on the "What did you load today?" thread.

 

[mikecr]

Necking down 26cal to 22cal causes 0.0019" thickening, which you should counter by turning from native necks (always new brass).

Necking down 24cal to 22cal causes 0.001" thickening.

 

[Kracken McGraw]

These tools area just find for measuring neck wall uniformity, but not for measuring "neck wall thickness". If you want a good measurement of neck wall thickness, you really need to us a micrometer, like this one:

Hornady Vernier Ball Micrometer 1

The Hornady Vernier Micrometer is designed to take precise measurements. Its unique design makes the Vernier Ball Micrometer ideal for accurately...

www.midwayusa.com

Not only can you measure neck wall thickness with this, but I find I don't really need those other uniformity tools to check consistency as this can do it too.

The ball mic is a biscuit for me to use for other purposes other than just measuring the neck wall thickness. That little ball just wants to slip when trying to measure loaded neck measurements. I will soon have to purchase the regular mic also.

 

[mikecr]

Calipers work fine for loaded neck OD.

 

[JFrank]

When you all measure wall thickness, do you run the mike down until the clutch ratchet engages ?

 

[bobm]

This is a delicate measurement, no need to ratchet in too much. A click or two only. My old Starrett lacks a ratchet feature. Here I am measuring freshly minted .22-250 Rem. necks made from once fired Hornady 6.5 Creed brass.

 

[PracticalTactical]

Until you have the pin mic or ball mic, you can always seat a bullet and measure the loaded round neck diameter. Its likely a more accurate value anyway even if a little inconvenient.

Once you have a bullet seated, you can also use a sizing bushing as a go or no go gage. I always do this to check my final loads to make sure I don't have any fat ones. If I find any that don't fall within a 0.001 tolerance, I sand paper the neck until it does.

Suppose you have a .332 neck and want 0.001" clearance... Use a 0.331 bushing as the max and a 0.330 as a min. This way you can sort out any extra sloppy ones from any fat ones.

To sand paper the necks, I use a wooden paint stir stick with sand paper glued to it. I spin the round in a Sinclair chuck. Usually just needs a light polishing to fit.

 

[257ack]

I no longer use my tube mic. I seat the bullet that I will be useing and measure the OD. I then set my neck turner to cut for .003 less than the OD. and I'm good.

 

[danny]

Danny, you're right. A pin anvil typically used in a 'tubing mic' won't work for our purpose, because our tube is tapered in shape and thickness (esp. with any donut). You would be measuring gaps.
For neck measure you need spot contact that a ball provides.

There are 2 other common flaws in what people are using even for ball neck mics:

1. They lack adjustable mouth stops. Cases vary in thickness from webs all the way to mouths. So if you're to see thickness and variance accurately, you need to set a datum of measure on necks. Will you measure 1/4 down necks,, 1/2 way, 3/4 down? Without a stop you'll be measuring all over the place and thickness will apparently vary on that alone.

2. They lack adjustable anvils. If you wish to creep into donut/neck-shoulder junction measure with a standard spindle, you only need an adjustable ball anvil. Tapering of the spindle does not remove remaining distance between anvil to spindle contact point (spindle center) to spindle edge.

Sinclair historically offered the best overall neck mics. But since Brownells bought them, Sinclair has lost or given up on some innovative products/suppliers. Their best ever neck mic is no longer sold, and their second best (the Starret with it's stand) hasn't been in stock for years it seems..
I couldn't suggest anything available today,, but you could build something.

"Sinclair historically offered the best overall neck mics. But since Brownells bought them, Sinclair has lost or given up on some innovative products/suppliers. Their best ever neck mic is no longer sold, and their second best (the Starret with it's stand) hasn't been in stock for years it"

Which one was the one that was best in your opinion? I know which was the one with the stand.

Danny

 

[mikecr]

This one:

Comes with a nice base, although I moved & combined to my Sinclair runout gauge base.
Adjustable anvil, so I can sneak right into neck-shoulder junction.
It's a really good clutch, and I added an adjustable case mouth stop.