URX 4 rail alignment, need help fitting rail...

[36CrazyFists]

Hey guys
Just purchased a URX 4 rail for my classic army M4.
It comes with 2 threaded rings which seem to screw into the barrel and on to the upper receiver barrel nut, however I cant seem to line the rail up right on the receiver, it seems to rotate too far and when it tightens the tops of the rails are out of line by quite a large degree.

Heres a pic of the receiver with one ring on and the 2nd ring, if anyone can help shed some light on this I would really appreciate it.


Thank you!

GAZ