Best adjustable gas block?

[NugginFutz]

Will the Superlative Arms fit a FF Forearm.

That really depends on which had guard you're referring to. If you are talking about the classic aluminum tube, then yes, it should. If one of the slim profile M-Lok or KeyMod hand guards that have become so popular, then it all comes down to the interior profile of that particular hand guard.

Another thing to consider is that Superlative's clamp on version has a slightly different profile than their set screw block. In order to accommodate the screws, the clamp on block has a slightly wider profile at the bottom.

I will tell you this, though. A Superlative clamp-on Adjustable Gas Block for a .936 barrel will NOT fit under a Caldwell free float hand guard. Of this, I am certain.