Mine came today,with my S.I.R.What is the flat side for on the grip?My S.I.R. weighed 18 oz on my scale ,with another 7 oz for the dieter grip.When you add optics,lights,etc.Thats going to get heavy,which makes a 141/2 M-4 barrel, with PF damn near max in weight for a barrel,in my mind.I am going to use it, but i got a feeling that my danieldefence 7 inch FF ras at a little over 8 oz that i ordered for another rifle is going to better be to my liking.

That's where you stick a rubber pressure-pad switch (like the Sure-Fire ones).  The grooves above it are for snaking the wire down to the switch.  

I Like my DD fore end for that reason.  When you start bolting stuff on your rifle every ounce you can save really helps.  Also that 8oz is even less when you take off your old barrel nut, delta ring, weld spring, c clip and HG cap.  The DD adds very litle weight.  

Pics of Daniel Defense unit?  Solid enough for optics?  Thanks.

From what I have been told by Wes(MSTN).  The DD is plenty sturdy for anything the other brands can handle.  ARMS or KAC.  Obviously it most closely resembles the KAC FF RAS and one of the only differences is the bbl. nut is aluminum instead of steel.  I have been thinking long and hard about getting one myself!

There was a post somewhere showing pics of the FF RAS and FF DD forend profiles/comparisons.  I think it was a few weeks ago but cannot remember the title of the thread!