The cross hair is not necessarily under Camera Forward Vector.
also, camera forward vector is prone to bugs when moving/changing direction.
Test the shooting by setting your line trace to persistent debug, then move left to right while shooting. You should see the line trace some times go off from where expected.
activate slowmo and you may even see the camera acting up.
Usually, you use deproject screen to get the vector (end point).
Then you get look at between gun muzzle and the world point.
And you use that as the vector for line tracing.