So my M&P15T has a front end Troy 4-Sided, 10" Free-Float Modular Rail Forend (MRF).
And the problem is that it slightly rotates back and forth and i can't figure out how to tighten it so it stops.
Since my front sight rests on it I can't afford to have it wiggle on it's free floating axis like this. Can anyone help me. I think I've tightened every bolt on my gun trying to fix this! Please help!

You could add some shim material to the contact points a thin bit of alum or plastic should do it.

You could apply some stock bedding material then sand to fit. But that might not hold up under the heat.

You could drill and tap several small holes add some brass screws than file them to fit.

cheapest apply some black electical tape.

If they are alum you could use a center punch on the contact points raiseing a little metal if to tight then file to fit.

Or may be some one else can give you a better idea.

Let me know how you end up doing it.