Originally Posted by ritam
I'm guessing your training involved projectiles travelling in a mostly horizontal direction. In a vertical shot, gravity is acting directly against the direction of travel, which means the downward acceleration of gravity is 100% against the direction of the forward momentum.
That's what I thought at first, too. Then I did a quick calculation:
The bullet leaves the barrel at about 700m/s. It gets slowed down by gravity by about 10m/s^2.
Assuming the bullet is travelling straight up and has no air resistance, it passes through 1500m (~4500ft) a bit over two seconds later, still doing slightly less than 680m/s.
Since the bullets usually don't reach much further up, I guess gravity effects can mostly be ignored.
Or did I miscalculate somewhere?