Now this is the case of projectile motion, the motion of bullet will be a projectile and its path will be parabola, the motion of bullet can be divided into horizontal component and vertical component i.e. motion along x axis and motion along y axis

Now the bullet is only experiencing one force in vertically downward direction because of its weight (gravitational force of earth) due to which its accelerating along negative y axis due to acceleration due to gravity, acceleration is uniform i.e. all the three equations of motion are valid in along Y direction, now there is no force in horizontal direction so component of velocity in horizontal direction or along X axis would remain constant.

The projectile motion of bullet has been shown in the figure

Now for an particle projected at an angle