Standard Deviation

[CharlieNC]

A full discussion about chrono stats.......

http://forum.accurateshooter.com/threads/chrono-statistics-and-excel-worksheet.3893642/

 

[Rust]

IMO there is way too much importance placed on SD.

Find a load that shoots well, if the ES for a string of ten is under 10 fps you're golden.

For instance I tried three powders, H4350, H4831 and RL-22 in a 6.5 X 284, with FGM and CCI primers, bullet seated lightly into the lands. Started powder charges in the mid weight range, why waste barrel life on loads that you know will be too slow to use. All shot over a chrono.

Found two nice loads, one with RL-22 and one with H4350. Both with single digit ES. The RL-22 fouled like crazy on a twenty round string requiring paste cleaning. The H4350 became my load of choice, ten years ago.

Haven't changed a thing since except when switching lots of powder or replacing a barrel, need to back off a bit for a string of test loads and check the velocity.