Temp/Humidity effects on projectile flight


Well-Known Member
Jul 17, 2008
Hi all, two questions that I have been chewing on for a while and have decided to throw it up for the experts.(Or those with a greater expertise than mine!)
1: In the Spring of 2009 with those warm sunny days (20 - 25 c) and green grass, I zeroed a new Nightforce scope on my 308. Recently, I began to get the feeling it was shooting low, and when I checked it, found point of impact 1/2"low at 100yds. Bullet is Remington 165 grain Boat tail Accutip factory.
The weather we have been experiencing in the South West of West Oz has been 30 c plus, accompanied with around 30 % humidity.
Would this have such a great effect on the point of impact ?
2: Angle Cosine Indicator - does using one of these require more mathmatics than the Angle Degree Indicator? Ie more difficult to use. I am not carrying ballistic software, but just a card that has what I deem relevant info.

And, be patient, you can teach an old dog new tricks ! :D

Warning! This thread is more than 14 years ago old.
It's likely that no further discussion is required, in which case we recommend starting a new thread. If however you feel your response is required you can still do so.