Grey Group has
photos of Tango Down rail mounted front sight. It is designed to be placed in front of Surefire X300, Inforce light or other mounted light. This design seems to be a way to mount tactical lights on top of gun without interfereing with other parts.
Currently, several available options for mounting tactical lights at 12 o'clock position is 1)
Daniel Defense rail systems 2)
Mossie Midnight mount
This would be an interesting item to look for
From: Grey Group