I have started to use a kesrtal 4500 weather device and the only stats I use is the Density Altitude(DA) , which is a calculation of the effect of Temp. and humidity on the air dencity. It then displays a reading in metres above sealevel. it basically tells you that the air density at the moment is simmilar to air dencity at a place much higher or lower above sealevel than you actually are.
This gives me an accurate indication if the gun has shifted since I last used it, providing I dotted the Density Altitude down the last time I used the gun, it tells me even before I fire the 1st shot in which direction it moved(up/down). But not by how much. The first sight in pellet tells me that anyway, so its just gadjetry fun I guess.
What it well tells me is that if I detect a shift and I see a change on the DA reading, I know its inviromentally related and not my gun messing about or acting up.
I've noticed a 1milldot shift with every 200m or so DA increase or decrease.
Use it dont use it, just fun messing around with the gadjets.