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Old 08-31-2020, 04:21 PM
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Nemo288 Nemo288 is offline
Join Date: Jan 2011
Location: Badgerland
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Originally Posted by Warren Sear View Post
How are you able to calculate pressures from chronograph data? Please explain. Are there formulas that you use?
I use the QuickLOAD internal ballistics program.
It comes with a fairly lengthy article about how it works and the limitations but they are understandably shy about divulging the exact mathematics.

Chronograph data is only a part of the input.
It's feedback actually.
Yes it's an estimation but the best one there is short of military software costing $thousands.
Once I get the program to predict velocities that are actually happening, I trust the pressure predictions to a certain degree.
The program itself claims to be more accurate for bottleneck rifle cartridges and higher pressure in the 50-60 kpsi range.
IMHO it usually over estimates the pressure for revolver cartridges when I compare the results to published numbers in reloading manuals and articles.
I believe it also over estimates the fill ratio as well for the powders I use.
This is fine and keeps me out of trouble when developing an untried load combo particularly in .445 where published data is scarce.

I hope that answers your question.
QuickLOAD is definitely worth the money but does take some time to train both the user and the program itself.
I keep a little salt around as well when I find myself getting too serious with the numbers.

This load performs exactly as predicted.
I tweak the case capacity and the Burning Rate slightly until it does.
Then I trust the ladder predictions better.
I would not shoot these in a revolver but I do in the Encore.
I limit break and lever action rounds to an arbitrary 45kpsi.
Attached Thumbnails
RANGE CHECKS-300xtp-30gr-imr4227-quickload-jpg  
"Everything 44"

Last edited by Nemo288; 09-01-2020 at 08:09 AM.
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