Ray curve for bullet gravity effect, or any way to make it

hey every one... i'm using raycast to shoot with my sniper, but it goes in a direct line... i want to make the gravity effect, but i don't know how to do it... if i could make a curved ray would be perfect, but i don't know how to do it. Some one can help me with this?

Thanks guys :)

Do a series of short raycasts, and alter the angle slightly for each one so that it starts heading down over a longer distance. So basically it's approximately a curve, broken up into a number of straight segments.