There are two components - horizontal and vertical. For a bullet fired straight up, horizontal component is negligible, as the bullet will spend enough time in

There are two components - horizontal and vertical. For a bullet fired straight up, horizontal component is negligible, as the bullet will spend enough time in flight for it to decrease due to air resistance. The vertical component is primarily determined by sectional density. Tumbling bullet spends a lot of time flying sideways, so its terminal velocity (where air resistance equals weight) is way less than muzzle velocity.