A bullet never rises as it comes out of a gun unless as the last two have said are done. the bullet only falls after it comes out. The arch that alot of people see on the side of ammo boxes is to show you the bullets best long range "0" and how much it will be high before it gets to "0". When on the side of ammo boxes or ballistic charts it shows a 200 yard "0" but then at 100 yards it's +3. That means that the bullet had to be aimed three inches high in order to get to a "0" at 200 yards. If the gun is placed perfectly flat the bullet comes out and goes down, never up. You said in your post as much of the bullet is pushing it down as up. When there is a arch in a bullet it is induced by the shooter trying to "arch" there bullets in at long ranges, which we all do. Put a scope on your favorite long range caliber and then sight it in at 50 yards. start backing up to 75, 100, 150 and so on and you will see the bullet only goes down after it leaves the gun.