Regulation of Double rifle question

[Peter Larsson]

If I get a double rifle regulated in say 15C at sea level.
Does it still regulate at a temperature near 40c at 1500meter over sea level?
My brno bolt rifle 375HH went about 1 dm higher at these conditions.
Guess it would be worse with a DR?

 

[grand veneur]

The reason for the zero deviation will be rather the temperature , not the altitude. 1500m is still for me no a big difference. IMHO a deviation due to the altitude is in practice much more noticeable very higher , but high up there a DR will not be used for hunting.

 

[Hunting Sailor]

I’m sure some of the Engineers on the Forum will give you the formula, but the higher altitude gives a difference in density of the air. So the bullet will fly longer with less resistance.
If I remember correctly the higher temperature also can maintain a higher % humidity so that would make the resistance higher.
Golfers tend to shoot 10% longer with any given club in Johannesburg vs here on the coast. JNB is at about 1800m above sea level.

 

[grand veneur]

The influence of temperature and altitude on ballistics is a complex topic with many uncertainty , and that is being discussed very controversially. The air resistance that changes according to temperature and altitude plays a role , but both factors have also a great influence on the burning rate of the powder with great pressure fluctuations when firing the cartridge. All is difficult because there are also differences among the cartridges of different calibers. If there are moreover shots at extreme angles , everything becomes even more complicated.

If you want to hunt in the extreme heat or cold , or in very high mountains , you have to test your rifle on site. I would never experiment with an DR at higher altitudes and temperature fluctuations. One already have enough accuracy problems with these objects at the same height and the same temperature. If it gets for hunting to the extreme , in the arctic or in the very high mountains , it's better you take a bolt action rifle.