I'm looking to build an M4gery, but have come to a fork in the road.  Do I get a RAS or RIS.  I know that the RAS is newer, but you still bump into a RIS occassionally.  I was wondering what everyone's preference was, and why.  

Also, does anyone know if there are any RAS IIs being issued.  I ask because I personally have no knowledge of whether or not they are, but was curious since I keep seeing RAS II's for less than the standard RAS.  Are people getting rid of them because they don't like them?  

RIS is for slim barrel Ars and RAS is for HB Ars. All I have seen issued is the M4 RAS.

RAS can still be used w/ Gov't profile barrels though, right?

Quoted: RAS can still be used w/ Gov't profile barrels though, right?

Yes.  The RIS just give you more leeway as far as barrel diameter, but it sacrifices some stability.  

The RAS will work anywhere from a Gov't profile up to a Colt or Bushy HBAR.  It won't work on pencil barrels or the HBARs from other companies.  

As far as the RAS II, I'ms ure there are a few floating around out there in military hands, but it was never adopted or issued in any signinfcant numbers.

Alright thanks.  I'm going to go w/ a RAS, b/c I found a really good deal on one, and it seems like it will suit my needs.