Just something simple. I have an M4 upper with oval handguards and no accessories. My options so far are:
Streamlight mount on sight tower for their M3 light.
Mount for Streamlight Scorpion light
Mount for Surefire G2 Nitrolon.
Lots of good reading in [url=http://www.ar15.com/forums/forum.html?b=3&f=20]Here[/url]