BC? Neither temperature or humidity affect BC. Both will affect trajectory, however.

quote:

Originally posted by gwahir:
BC? Neither temperature or humidity affect BC. Both will affect trajectory, however.

Actually, they do affect the BC. BCs are not constant; they change based on the density of the air or even velocity of the bullet, and technically, the yaw.

The shape or form factor of the bullet does not change, but that is only part of the calculation used for BC.

Writer,I stand corrected.
Never assume a BC. Always verify on target.

The bc of a bullet changes through the velocity curve that is why Sierra gives multiple bc’s for their bullets at different velocities because the bc does not stay constant. Yes humidity can have an effect on a bullet how much depends on the range. I doubt you will see much change 800 yards or less but beyond that you will see some and beyond 1000 yards you will see more of it. Cooler air is more dense and is harder for the bullet to cut through causing more drag than warmer air. I have even noticed this at 600 yards when it drops below 10 degrees. My velocity does not change much with the Hodgdon Extreme powders most are less than 20fps difference between summer and winter but I need more MOA to hit the bull because of the cooler air. When it is colder out you also can see the bullet trace much easier when spotting for someone because the air is thicker.