In the vertical plane while the bullet is moving upward away from the center of the Earth, yes, technically.

But a better way of thinking about gravity is that it is a constant force that acts to change the direction of a projectile in flight by accellerating it toward the ground. Drag, on the other hand, varies based on a number of variables, and effects a projectile no regardless of the projectiles relative velocity to the ground.

This means that if a fighter jet were to fire its cannon straight down toward the ground, gravity would provide an additional accellerative force that would tend to make the bullet fall faster. However, the force of drag created as the bullet passes through the air is of a much greater magnitude that the accellerative force of gravity and would cause the bullet to slow down considerably before the bullet hit the ground. Now, if we were to assume that the bullet was fired from an extremely high altitude, and that the density of the atmosphere was constant (which it's not, but this is for simplification and visualization purposes only), the bullet would eventually slow down to the point were the accelerative force of gravity exactly equaled the force of aerodnamic drag, and the bullet would settle into an equilibrium, or terminal, velocity.