Speaking of chronographs

[ubetcha]

Looking at some past posts about chronos, I just ordered a Magnetospeed Sporter . Should be here tomorrow. Now I have to understand some readout's that will be on the data. Such as extreme spread and standard deviation. What do they mean , what relationship do the have with velocity, how to tell if the readings are good or bad, etc. Should I shoot a 10 shot group to get an average mv ? It seems the older I get, the harder it is to understand somethings.😁. Thanks for any help.

[Rcmaveric]

One of the few things crom a few college courses that helped me was statistics.

Extreme spread is the differece between the fastest and slowest shot. Standard devistion or SD is basicaly your average deviation from shot to shot.

For load development i take 5 shot tests groups. Once a good load is found. I do 10 shots to test repeat ability. Then if you want a good accurate representation then i do 25 shots. The more shots you take the greater accuracy of a statistical data.

For reverence factor ammunition goes for an SD of 30 or 40. So if you are below that then your quality of ammo is better than factory.

Sent from my SM-G950U using Tapatalk

[country gent]

I work up loads with the chronograph when I find " the load" I then test a couple 10 round groups on the next outing and then over several different days.

[fredj338]

RC gave a good description of what the ES & SD mean. As to what does that mean to you? In theory a load with smallest ES & SD should be more accurate. Reality, not always. I have had great chrono data that wont shoot well as loads with larger spreads. Every barrel is a law unto itself.
For long range rifle, smallest numbers coupled with good accuracy means it should be more accurate as you pass the 300y mark. For SD, single digits in rifles is really good. In pistol ammo, I am happy with SD in the teens & this is only when I have to make power factor. I get 3 shots to make PF so if the spreads are small, better chance that happens.

[Larry Gibson]

Check these two sites out for some excellent information.

https://oehler-research.com/white-papers

https://oehler-research.com/wp-content/uploads/2017/11/M35-Instr-2015-PC.pdf start on page 17 of the M35P manual for some excellent basic explanations.

[hermans]

Check these two sights out for some excellent information.

https://oehler-research.com/white-papers

https://oehler-research.com/wp-content/uploads/2017/11/M35-Instr-2015-PC.pdf start on page 17 of the M35P manual for some excellent basic explanations.

Very good information here....every shooter that uses a chronograph can benefit by reading this, especially from page 17 of the 35P manual, as pointed out by Larry!

[ubetcha]

Thank you Larry for the link to the M35P manual. That does seem to explain alot. now to read and read and read for it to really sink in. :p. Page 21 looks to do the explaining