MOA and Temperature

[houston]

For you shoters who shoot long range all year long, meaning temps from 90deg. in the summer to 20deg or less in the winter what do you see for a MOA change. Im finding it takes an extra minute for every 30-40 deg drop in temp at 1200 ft above sea level. I know the barometer plays a big role also, but mainly with the hotter temps, stilling learning only been at it a couple years. Thanks jeff~

 

[Michael Eichele]

Yes temps have a HUGE impact on trajectory like pressure does. Humidity has the least effect in regards to enviormental influences. Temp and pressure make up the majority of air density. Altitude only effects pressure. In the end, it is the raw pressure that determines bullet flight and not altitude in and of itself.

Play with a ballistic calculator a bit and you will see that air density has a HUGE factor on bullet trajectory.

My 308 has a difference of over 10MOA (over 100") of drop at 1000 yards between the -10 degrees/sea level that I practice in versus the 60 degree/5000' above sea level that I hunt dall sheep in.

Just changing from -10 to 60 degrees (staying at sea level) changes the drop at 1K by nearly 60". Thats just the difference in 70 degrees of temp spread.

 

[Canadian Bushman]

Not only environmental but temperature can also affect the burn rate of the powder in your rifle shell. Some powders are temperature sensitive and some are not.