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I have to make an assumption to answer your question, and that is that the rifle's sight is being aimed level with the ground. If that is so, then the bullet actually does rise slightly, for most rifles. I say "most rifles" because most rifles have their sights mounted above the barrel. When a rifle's sight is adjusted, it has to be adjusted for a specified range. Refer to the following picture.

Because the sight is above the barrel and we want the bullet's path to cross the path of the sight, the barrel does in effect get aimed upward just a little bit. Then, as the bullet falls in its flight, it will cross the path of the sight a second time!! So there are two ranges at which the rifle is sighted!! I have a .22 rifle with a scope, and I have sighted in the scope at a range of 25 yards. It turns out that the second sight point (the secondary range) is about 75 yards for my rifle. The exact distances depend on the type of rifle and how high up the sight is from the barrel.
You can think of this as pointing the sight DOWN to make the sight's path cross the path of the bullet, but it is the same effect: if the sight is then pointed at a target the bullet will rise to hit the target (relative to the sight).
John Link, MadSci Physicist

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Bullet Trajectory

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There is some theory of actual bullet rise out there due to all pressures around the bullet is not the same. I never quite dug into why or how, and its supposed to be not much. But its supposed to be a real phenomenon.

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Thanks for the pic Reb. Was thinking of drawing it but did not have the time. You are right about how we hold the sight level to achieve our "0" but arch the barrel. That is what I was trying to say in the post but does not always come out right. But what I was trying to compare it to was a perfectly level barrel regardless of sight, the bullet only goes down. It is the sight that we set on a downward angle in relation to the barrel to get the barrel pointing up to achieve our POI at said "0". Also good link on the scientist page. The bullet only goes down, if it is going up then it is induced by the scope or sights to make it first go up and then down.

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I believe that big country is also right in this situation. Due to the shape of the bullet and the speed that it is going, the pressure on the top and bottom side of the bullet will be different. The moving bullet when shot out of the gun will cause ahigh atmosphereic pressure on the lower side of the bullet and a lower pressure on the upper side of the bullet. The high pressure will then try to move to the lower pressure in order to equilize the pressure around the bullet. This will cause the bullet to slightly move up untill the bullets shape slightly modifys. This is the same basis of how a air plane works. The wind is also an exampl of that. You have a high area of pressure and a low area of pressure and the high pressure moves towards the low pressure causeing wind. And anyone who has ever seen wind( all of us) will know that the wind can move objects just the the pressure will cause the bullet to rise.

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It is a shame that it even has to be explained with diagrams and such.

I'm really surprised that there are those that actually think the bullet rises all by itself.

Thanks Wayspe for the explaination, Very well done.

Reb, thanks for the diagram.

And Hotburn is correct in knowing those that don't agree didn't pass science class.

Oh, by the way, there will be dentention for those that failed this test.

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Izaak Newton is rolling over in his grave.

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ReDoT - ReReadThe math/physics problem:
Key words are horizontally aligned rifle. Therefore, the bullet will not be traveling in an upward direction. It begins to fall toward Earth at the same rate as the dropped slug only traveling forward at the same time. I think thatthey will hit the ground at the same time.

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My server has been down. The key part is that the barrel is horizontal, not the sight. I saw it on the History Channel also and thought it was interesting.