I am swapping barrels on two uppers for a friend who will later be installing a Knights RAS 5 rail system.  I am not familiar with the entire workings of the RAS 5, but I did some quick looking around online and see that it can be installed without removal of the gas block/front sight, but what I don't know is whether I should install the barrell for him with or without the delta ring.  Also, should I remove the front handguard holder (not sure the official name, as it is not illustrated on the parts diagram.)

You'll need to have both to install an M5 RAS.

it's a two piece non-freefloat.  Goes on like a regular set of handguards.  The only difference being there is a little piece that straddles the gas tube.  If it's the M4 RAS, then D-Ring removal is required...