Actually, what is a difference in between the " Extreme spread and standard deviation". I would assume the spread over a distance with indexed pellets, but the deviation is a measuring device uncapable of consistently calculate?
I am asking based on having several chronographs in the past (indeed for archery only) but I had a situation having several brand and model in the same time. I compared them simultaneously and they showed different values (from same brand).
Marginal error how the units sensors measure and calculates....lets take this in consideration.
Shooting arrows - or pellets, in let say 30 second sequence, within 5 minutes of measured time, same ambient temperature same air density, same indexed projectiles, ,,why is a deviation?...on any chosen brand same units or multiple units.
I ended up having this "ultrasound" - shot through hole type chronograph from aliexpress, not because I like it the most but because I got tired of spending money further (for many years again and again) on any sophisticated marketed units. This one showing me the most tightest numbers (like it or not)... I redesigned a $200 Chinese franken 22 project gun....the deviation is max/min 3 fps +/- for a best grouping @ 50M (I call this a pretty f*n amassing job I did with this f*n cheap Chinese crap. Sorry guys for my language, I just wanted to express finishing my standpoint.
Are these numbers any accurate for total deviation? I have no idea, to prove some shall spend 20-30x more $ for some heavy commercial unit.
Edit:
The problem with this chronograph unit is....it is not like changing tires on my car with buddy's and having a case of beer