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Discussion Starter #1
Ebay is some sort of disease.
Many years ago, I made a tubing mic from a high quality but sprung 0-1". The Etalon mic was probably $500 worth before being ruined. It reads in 'tenths' (ten thousandths of an inch)
Well, ebay has an electronic digital tubing micrometer that direct reads to .00005 (fifty millionths) for $55! Sign me up!
It came today. A NASA contractor won't like it but for a precision handloader that's turning necks, its a very good deal and a most useful tool.

If you really like measuring stuff, here's a neat tool and a very affordable price. The large part of the spindle is a slip clutch that is very repeatable but not Browne & Sharpe smooth. I checked it against gauge blocks and got plus or minus .00005. It's an odd thing to use because the spindle is not graduated in any way. All readings are by LCD run off one watch battery which is included.

Once fired FC 30-06 neck thickness varies from .0126 to the shown .01465 at the thickest. Two thousandths variation is about normal for factory brass.
 

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Discussion Starter #3
I've got four digital calipers, a height gauge and a DRO for the Z quill on the mill. The first thing I check is to see if it has an auto off. Two don't and those are the batteries I keep on hand.
My main caliper is a Mitutoyo 6 inch digital with a solar panel that keeps the battery up. It's at least ten years old with the same battery.
Ebay tip--- purposefully misspell your search. Sometimes, a $200 instrument can be bought for a couple bucks because nobody saw it.
 

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I like that it has a digital readout rather than a standard micrometer barrel style. I'm still using my 30 year old K&M, I think I paid more than 55. back then.
 

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Elk Whisperer (Super Moderator)
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They're called ball micrometers. Sinclair makes an exception one, I know, I use mine constantly and there's no batteries.
I use a Starrett 577 ball anvil mic to measure bearings, same thing I think. No batteries required.

Never thought to use it to measure neck wall thickness.

RJ
 

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I use a Starrett 577 ball anvil mic to measure bearings, same thing I think. No batteries required.

Never thought to use it to measure neck wall thickness.

RJ
There are reasons, neck walls do vary in thickness. So trimming the walls is helpful to deal with uniform neck tension on the bullet when you don't crimp.

I was lucky, when the old Sinclair staff and I were sending stuff back and forth, we touched on this and they fired off one to me to try. I love the thing, you can't over tighten it and you get more accurate reads. Best of all it's on a stand which also makes it easier.
 

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Discussion Starter #8
Actually, a 'Ball mic' and a 'tubing mic' are totally different.
The Ball mic has a semi-hemispherical anvil instead of a flat. They're mostly used on bearing shells.
The Tubing mic has a spud that fits inside the tube to measure wall thickness.

Ebay has both with great pictures.

A micrometer stand is SO handy!

BTW-- The digital tubing mic I bought has a .187 spud so is NOT suitable for measuring .17 cal. necks.
 

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Elk Whisperer (Super Moderator)
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So, the 577 won't work except on maybe 50 cal, but I can still use my calipers to measure neck thickness. The real dial set will read to .0001", the digital electronic wizard set only to .0005" .

RJ
 

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Discussion Starter #10
True. The ball mic will work for very big cases. The calipers have flat jaws so are measuring thickness plus the versine of the radius. That doesn't give you a true reading but fine for comparisons.
Here's a set of 4" calipers that were sent by mistake and ended up keeping them because they are handy. Even with the needle-like jaws, they measure .0002 big on case necks.
 

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Actually, a 'Ball mic' and a 'tubing mic' are totally different.
The Ball mic has a semi-hemispherical anvil instead of a flat. They're mostly used on bearing shells.
The Tubing mic has a spud that fits inside the tube to measure wall thickness.

Ebay has both with great pictures.
According to you Sinclair International is wrong. I don't think so given the number of decades Fred Spent working with high power and 1000 yard shooters, not to mention the number of invocations Sinclair came up with. If you'd gone to Camp Perry, the Bar B Ques were great and a chance to yak with Fred.

True. The ball mic will work for very big cases. The calipers have flat jaws so are measuring thickness plus the versine of the radius. That doesn't give you a true reading but fine for comparisons.
Here's a set of 4" calipers that were sent by mistake and ended up keeping them because they are handy. Even with the needle-like jaws, they measure .0002 big on case necks.
Only problem with those is you'll miss the variations in neck thickness. When I load, I want to know thinnest and thickest points in the case neck. It's why I don't bother looking for other answers
 

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You can go on Amazon anvil and find both types called ball or ball anvil or spherical anvil micrometers. I did not find the spherical section anvil micrometers called tube or tubing or reloading micrometers, though. That seems to be reserved for the type in question. Here's one called a "reloading tube ball spherical anvil" micrometer, just to get all the bases covered. Probably done for the search engine.

Whatever one you use, get a base for it, even a cheap one. I couldn't believe how much faster and more repeatably I could measure with it in my cheapo Harbor Freight base.
 

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Uncle Nick-- That's the tool I bought and I'm loving it. The clutch has gotten smoother and more repeatable with a little use. I saved $8 and that's always nice.
I have five rifles with BR tolerances and neck thickness is critical for safety and accuracy.

It's interesting to me to find a few necks that have 'grown thicker' on one side than the other. My 6mm Cheapshot has a .2627 chamber neck. I turn all necks to .0088 thick and bushing neck size to .260. I have some case with 25 firings that have .009 necks on one side now. All were military cases that when cut off at the shoulder showed thicker case walls on the side that became thick. There's some weird metallurgical magic going on. I don't shoot those rifles on paper and haven't noticed any tendency to fling a flyer, but which now I hadn't destroyed the cases and experiment with them. .0002 is NOT a critical amount unless you're shooting for money.

Fred Sinclair might have called a micrometer with a ball on a stem a 'Ball Micrometer'. I've done it, too. You'll soon see that a true 'ball micrometer' is no good for measuring neck thickness. Tubing micrometers do.
 

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You can go on Amazon anvil and find both types called ball or ball anvil or spherical anvil micrometers. I did not find the spherical section anvil micrometers called tube or tubing or reloading micrometers, though. That seems to be reserved for the type in question. Here's one called a "reloading tube ball spherical anvil" micrometer, just to get all the bases covered. Probably done for the search engine.

Whatever one you use, get a base for it, even a cheap one. I couldn't believe how much faster and more repeatably I could measure with it in my cheapo Harbor Freight base.
Try one of these Nick, they work great.


99939
 

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Fred Sinclair might have called a micrometer with a ball on a stem a 'Ball Micrometer'. I've done it, too. You'll soon see that a true 'ball micrometer' is no good for measuring neck thickness. Tubing micrometers do.
Fact check, Fred Sinclair has a very long history of improving accuracy especially with ammo and helping the guys at Camp Perry.... and then we have Jack Belk... Shall we post Jack Belk's resume on all the time he's worked in the industry?

Sinclair ball micrometer is very accurate and it works very well, if it didn't Brownells which now owns the Sinclair line would have pulled it a long time ago. Of course I can post a picture of the 3000 M118 cases I did with it, not including all the M72 brass I've reloaded. Of course there is the fact that you don't check neck thickness is just one spot, you spot check more than one which makes it more accurate.

Jack,, this is like the time you said the 1911 has a toggle. I darn near fell out of my chair laughing. That rates right up with your knowledge of the TRW "you were issued".

Can we say "blowing smoke" boys and girls?
 

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The Hog Whisperer (Administrator)
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Let's not argue about semantics. Waste of time. I've seen them called both, and sometimes "ball/tubing" mic, in various industry publications.

Thread closed.
 

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Elk Whisperer (Super Moderator)
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This has probably been done, but I got to cogitating over the weekend and came up with a "continuous" neck measuring idea. What if a guy made an "anvil" out of say 3/32 and secured it really close to it's anchor point then positioned your dial indicator over the center that of that. By rotating the case slowly one could get 360° measurements like you checking case runout.

Thinking out loud

Semantics is several differen versions of truth in the eyes of the different tellers. Ki da like a myth. If you tell it long enough it becomes truth, buy if you tell the truth, you don't hafta remember so many myths.

RJ
 

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RJ,

Check out the Redding tool. It has bushing close to the ID of the necks to keep them lined up. The NECO case gauge has a similar thing, but it's a tree of diameter steps.


Rojkoh,

Yep. That's basically what I have with the micrometer stand hanging onto the back of the "C" of the micrometer, but that's a neater package.
 
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