Home Forums Hunting & Shooting Ask The Gunwriters Formula for Standard Deviation

I have an older chronograph which does not have the standard deviation feature. I did have a fairly easy formula for this but somehow I lost or misplaced it. I Googled for the formula but it was a fairly complicated procedure. The one I had was fairly simple and I found it valuable in developing handloads for both pistol and rifle loads. Can anyone offer any help on this? I would sincerely appreciate it.

Thanks in advance.

Roundup