Well, I found out why Barnes Bullets "like jump" ...

[moxford]

All measurements were made with a Mitutoyu micrometer

Micrometer or caliper? If micrometer, what technique did you use for mounting the ogive jig /Hornady comparator?

My measurements were only with a Mitutoyo caliper + Hornady comparator, so not as accurate as a micrometer.

 

[Varmint Hunter]

I had a standard deviation of 0.00066215. This was calculated by the Excel spreadsheet I was using to log all the measurements.

All measurements were made with a Mitutoyu micrometer

I'd be very interested in knowing more about a gauge that can measure out to the eighth place. Is that 1/hundred millionth of an inch?

I must be misunderstanding something here.

 

[Troutslayer2]

If this kind of thing bothers you I wouldn't suggest the Accubond Long Range.

 

[Hugnot]

^^^

Wonderman4,'s SD having lots of "0's after "." indicates a SD of zippo. SD produced as SQRT variance by excel, input data most likely to nearest thou.

My paper worksheets produced by excel & other are covered with coffee stains - coffee never makes me jiggy but it makes me happy & wise.

 

[wonderman4]

Micrometer or caliper? If micrometer, what technique did you use for mounting the ogive jig /Hornady comparator?

My measurements were only with a Mitutoyo caliper + Hornady comparator, so not as accurate as a caliper.

I used a micrometer, just as I stated in post #13. I machined a 0.308" diameter bushing that I use to measure all bullet related things.

I did NOT use a comparator.

 

[wonderman4]

I'd be very interested in knowing more about a gauge that can measure out to the eighth place. Is that 1/hundred millionth of an inch?

I must be misunderstanding something here.

Standard deviation is calculated, not measured.

 

[wonderman4]

^^^

Wonderman4,'s SD having lots of "0's before "." indicates a SD of zippo. SD produced as SQRT variance by excel, input data most likely to nearest thou.

My paper worksheets produced by excel & other are covered with coffee stains - coffee never makes me jiggy but it makes me happy & wise.

Input data was to the nearest 0.0001.

 

[Varmint Hunter]

Input data was to the nearest 0.0001.

Got it.

 

[Hugnot]

Not enough coffee - should have been - "0's" after "." (Zeros after decimal point).

To me an ogive measurement to nearest .0001 seems sort of excessive & for my casual shooting using hi-grade bullets right from the box a .001 spread works out good. Bullet shape, tangent ogive vs. secant ogive, might also be a factor. I prefer to seat bullets deep enough to enable a random excessive length ogive bullet not to have land contact.

 

[quigley257]

I was appalled at the BTO as well as OAL measurements of the first couple boxes of Sierra .224" 95gr SMKs that I bought. It is hard to complain when they shoot like this though...

 

[Taylorbok]

I used a micrometer, just as I stated in post #13. I machined a 0.308" diameter bushing that I use to measure all bullet related things.

I did NOT use a comparator.

gonna assume you mean .300" your bullet would slide straight through a .308".

 

[FEENIX]

I measured 15 bullets (with a caliper and Hornady gauge) that were machined with a modern CNC machine. As you can see, despite the type of tooling enhancement, there is still a .005" spread. I plugged the numbers into an SD calculator (https://www.calculator.net/standard-deviation-calculator.html.), and below is the finding.

 

[Varmint Hunter]

I measured 15 bullets (with a caliper and Hornady gauge) that were machined with a modern CNC machine. As you can see, despite the type of tooling enhancement, there is still a .005" spread. I plugged the numbers into an SD calculator (https://www.calculator.net/standard-deviation-calculator.html.), and below is the finding.

View attachment 408431

Are you sure about that figure? I rechecked the math and I'm sure that you are off a few trillionths.

 

[Troutslayer2]

I like to find a load that is tolerant of a variance. Bonus- I don't need to chase the lands. Bonus- I don't have to measure every bullet off the ogive.