Flat top receiver?
Front sight housing pinned to the barrel or rail with detachable front sight?
Are these the sights that came with the rifle or added after?
Sounds like the front sight assembly is the wrong height and you have one intended for a rail the same height as the flat top receiver rail rather than one intended for a railed front gas block, which is lower. That sight assembly would appear taller when mounted to a rail on the same level.
Scott