DD RIS II rail question

[Icculus]

Ok so I think I finally almost figured out the differences between the all different DD rails.

M4 - interrupted rail, standard barrel nut install
Lite - thinner profile, uniterrupted rail, proprietary bolt mount (possible gun smith install)
Omega - uninterrupted, allen key user installable, removable bottom rail, swivel mounts
Omega X - basically the Omega but with the Lite mount system

What I don't get is what is the RIS II and why do people seem to go crazy trying to find them? The site says something about being able to free float a M203 to it but--aside from possibly the military members here--who really has one of those. Is there some other wonderful feature I missing?
:confused:

[RAM Engineer]

Ok so I think I finally almost figured out the differences between the all different DD rails.

M4 - interrupted rail, standard barrel nut install
Lite - thinner profile, uniterrupted rail, proprietary bolt mount (possible gun smith install)
Omega - uninterrupted, allen key user installable, removable bottom rail, swivel mounts
Omega X - basically the Omega but with the Lite mount system

What I don't get is what is the RIS II and why do people seem to go crazy trying to find them? The site says something about being able to free float a M203 to it but--aside from possibly the military members here--who really has one of those. Is there some other wonderful feature I missing?
:confused:

Of the rails you've listed, only the Omega uses a standard barrel nut. Not the M4 rails.

The RIS II is closest to the Lite rail. The main differences are:
1. RIS II has anti-rotation protrusions.
2. on the FSP models, the RIS II has true continuous rails past the FSP. The LITE has cut-outs to enable the FSP pins to be removed and replaced.
3. RIS II freefloats the M203 as you said.
4. RIS II has actually been tested and fielded by the US Military.

[Icculus]

Thanks for the clarification and details. Saw the holes for the fsb pins you were referencing. Don't quite follow on the anti-rotation protrusions though.

ETA: The RIS II also appears ,how shall I say, less hollowed but also seems to carry a couple extra ounces penalty over the other models of equal length for that added reinforcement.