New Chronograph, Extreme Spread & Standard Deviation

[JimTom]

G’day All.

After years of successful reloading I have purchased a chronograph to use at the range to see how fast my loads are actually travelling, and to see how good my reloading actually is in terms of SD and ES.

I am mainly a hunter, not a competition shooter. In saying that I strive for the best accuracy and all of my reloads are well under and inch at 100m.

I do understand that the smaller the number the better, however what would you consider as an acceptable set of numbers for extreme spread and standard deviation, and would your answers vary depending on cartridge? ie, I would’ve thought that 100fps ES would be more critical in say a 22 Hornet than what 100fps would be in a 300 win mag.

Thank you in advance for your input.

[SCJ429]

For hunting an Extreme Spread under 30 would be great and a Standard Deviation in single digits you are over the moon. At the end of the day, it is the group size that matters. I love the data but you can spend a lot of time chasing low numbers.

[JimTom]

Yes I agree mate. It has been an interesting experiment for me, having not delved into the world of chronographs before. My best group from my last range session had an ES of 35 and a SD of 7 which I thought would be considered pretty good. Just wanted to hear from someone who knows more about this than I do.

[SCJ429]

How big was the sample and resulting group?

[Sarco]

I chronograph all my loads, rifle, pistol, even my air rifle and air pistol have been chronographed.
That being said, I pretty much only target shoot these days, and am a data person and probably OCD as well.
However, IMHO the more consistent your ammo is the better. As such, the less extreme spread and deviation the better.
While a good group at 100M may be still a good group at 200M, it is the longer distances that bring consistent ammo into its own.

[JimTom]

How big was the sample and resulting group?

Five shot group mate at 0.45”. Thing is I had some reasonable groups with higher ES and SD, and conversely had some terrible groups with a smaller ES and SD. Guessing that's the human factor in there causing that though.

[animalpest]

Low ES and/or SD does not always relate to group size.

If you can get ES below 30, a SD less than 10 AND good groups then you have a winner.

I have gone down the rabbit hole chasing lowest SD and ES and while fun, it can be very time consuming to get consistent results.