Neither had I, but I had heard of the Coriolis effect. Lapua explains both.

https://www.lapua.com/ballistics-app-ti ... k-c4hlr579

The math is complex, but the concept is pretty simple. If you fire a bullet towards the east, the bullet will resist gravity and if you fire a bullet towards the west it "gains" gravity. While not as big of a factor as wind, drag, and Coriolis, the Eotvos effect can alter bullet drop by as much as 1%. No big deal at 300 yards but 1,000 and beyond it does matter. The greatest impact is along the equator and reduces as you move north or south from the equator.

The earth's rotational effect is why we launch rockets towards the east. Think of it as either a boost in speed or reduction in gravity.

Thanks Bill

Interesting, Thanks.

Wow! Cool! It makes sense. Thanks for that!