Effect of environmental factors on standard deviation.

How significant would the difference in the velocity be with the variables like temperature and whatnot?

It might be cool to do some regression stuff with it, though probably meaningless

Actually, maybe not… When @sungazer is back from his holiday and online, I am sure he can share some of his doing science records. Fairly sure he would have experimented and kept records of this.

If @Gwion is around, would be good to hear from him on this too.

@Brett you too.

Temperature is a big one, both heat soak of the chamber area and keeping ammunition in the sun, often go up a few clicks on hot days, thats generally the only one i’ve had to account for at the distances i shoot at, see alot of blokes keep ammunition in insulated containers like lunch boxes and what not

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Just got back from my holiday in the tropical paradise and the cold chill of Victoria is a welcome break at least for one day.

I do try and keep my ammo out of the sun and also out of the car on a hot day. However the maximum difference from the 38 deg to a 8 deg shooting day the maximum that I would attribute directly to temperature would be 1/8 of MOA over any distance out to 1000 yrds.

Cold air moving down a hill I have noticed will move the vertical around but that is more like wind rather than direct temperature.

I do use ADI powders however and mostly AR2206H other from BM1 to AR2213sc I have found all to be very temperature stable.

Is that more of a thermal expansion thing? So with heat there would be more variance in the precision due to the everything expanding, possibly at different rates.

Does that also mean if you were to sight the rifle in at certain temperature, that temperature should theoretically be the most accurate? Or just as cold as reasonably possible is best?

I was more talking about .22lr’s as well when clickin’ up just to clarify :ok_hand:

I’ve noticed more of a difference between high and low pressure days than hot and cold days but that’s purely anecdotal and wind direction may also have been a factor in the change of zero.