I don’t think you could do this as a preset, instead you would need some stock footage of a shell falling and then composite in.
One possible way to do this would be to get a picture of a shell and start it at the top of the screen, move a few frames along and move the shell as if it was falling and rotate it a bit, a few more frames move it further down and rotate a bit more, keep doing this until it is off the screen all together. Render this out and you now have a quickly made bit of stock footage of a shell falling.
If you do this a couple of times with the shell falling in a different way each time you could make a small library of shells that could be used for your shot.
Using the above technique I quickly made a couple of sample shots to show what it could look like. shell_fall_one.avi shell_fall_two.avi
I hope the above helps with your shot.