I agree, bullet velocity should be horizontal, however, the effect of gravity leads to a change in distance which the bullet needs to travel. Therefore aiming straight at the bulls eye, the displacement between the barrel of the gun and the centre of the target is 200m, the hypotenuse formed by the displacement from barrel of gun to actual bullet contact with bulls eye will be incrementally bigger. The angle should be small but not negilible. Hence, given this, how can the suvat equations be used given that either the theta or the t is required to solve.