I decided to complicate my life and got the 21st century concentricity gauge and need your advice/opinion. Based on the 2 videos below is it safe to assume that the runout of the round is about 0.001 (TIR/2)? Is measuring at the neck and at ogive the best way to go?
Concentricity measurement opinion/advice
- Thread starter LA260
- Start date
I don’t know what the proper math is, but I would call that 3 thou of runout if I was talking about my own loads.
That is not your runout. The numbers you see on the dial is your TIR (Total Induced Runout) to get your Actual Runout you need to divide that number in half. So your actual runout is half of what your reading on the dial. Bottom line, your ammo has very little runout and is good to go..
https://metalcutting.com/circular-runout-vs-total-runout/
https://metalcutting.com/circular-runout-vs-total-runout/
How do you come up with .003 runout? That dial is measuring in .0005 increments line to line. I show the needle moving .001 - .0015 TIR which means his actual runout is half that in the first video.
Circular runout (what he is measuring in that video) is equal to total indicator reading (.0015") not 2X TIR or 1/2 TIR
A real basic primer on what it is: https://www.gdandtbasics.com/runout/
A real basic primer on what it is: https://www.gdandtbasics.com/runout/
For me maybe it's because I'm watching it on my phone I thought the units on his dial indicator were in 1 thou increments. I couldn't tell they were .0005 but still did the math wrong it's early 
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Since I started using a Co-Ax a few years ago my concentricity gage gathers dust... Virtually every cartridge barely moves the gage. Not even worth checking anymore...
Not according to ASME Y14.5. Circular runout = full indicator movement.
The gun world can call runout whatever it wants, and can call runout gauges "concentricity" gauges. It's still wrong.
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You’re right, missed that those were half thou lines. I’d call it 0.0015
I dont know about ASME Y14.5 but its been practice for as long as you want to go back and research that TIR (total indicator reading) / 2 is actual runout when measuring ammo straightness.
https://en.wikipedia.org/wiki/Total_indicator_reading
....... If a shaft has 0.1 mm TIR, it is "out of straightness" by half that total, i.e., 0.05 mm.
The bottom line is, his ammo is showing .001 - .0015 on the indicator which either way is very straight ammo.
I'm not going to argue with you. I do this for a living (for the last quarter century) and frankly I don't give a shit what the internet says or what a layman's interpretation of GD&T is.
I told you what us professionals in manufacturing industries use and I gave you the source document if you wish to learn. Do with it what you will.
I assumed that measurement precision would be important in a precision rifle forum. I'll give you a freebie since the spec isn't free
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