It's ignored in practice when firing long guns at 5,000 yards.
The minuscule effect is overwhelmingly dominated by everything else. Heavier, longer range shells from naval guns, yes - rifles, no.
* Opinion of a ULR shooter: https://www.youtube.com/watch?v=KP7IKshdiiY
* Range Proof: https://www.youtube.com/watch?v=7owwTz7Z0OE