You have to remember that you're using two different layers and that the X,Y coordinates of a rotated layer will be the same, even if visually the object appears at a different position.
<img src="http://dl.dropbox.com/u/36472942/construct/forumhelp/LayerRotation.jpg" border="0" />
Hopefully this figure will illustrate what I mean.
The little black rectangle is your object.
Both black X's marks the spot.... I mean represent your imagepoints.
The big black rectangle is your non rotated layer.
In red, the rectangle represents a rotated layer, and the red X's are the visual position, according to the black X's coordinates (both the red and black X have the same x and y for C2).
It is doing exactly what you say, it spawns at the coordinates of the image point.
But visually it is not the spot/angle you're looking for.
So solution is to spawn the bullets on the same layer as the plane. This way the position will always be the good one.
Else, you need to recalculate the position thanks to a bit of sin/cos. (there were already quite a few posts about this issue since the beginning of the competition).