Hey all. I've got a few questions regarding this system. Here goes:

First off, which one do I use if I dont want to do any gunsmithing? I've heard there's one that can basically replace my M-4 handguard. I dont want to be bothered with removing anything 'cuz my compensator is welded in place.

Second, if there's one that replaces my handguard, will it have any wobble or other movement? I want to use it to move my EOTech 552 forward and if it's going to wobble obviously I can't use it to mount an optic. What's the story with that?

Third, who has these cheap? What will I pay?

Finally, if anybody has a pic of one of these with a 552 mounted I would appreciate it greatly.

Last (almost forgot) are US forces using Knight's RAS or do we use SIR or what? Thanks, and looking forward to responses.

Semper Fidelis.

The RIS, the RAS, and the RAS II can be installed without any gunsmithing whatsoever.

The RAS II is the only one of those three that will remain stable with no wobble over the course of time.  That is because a small section of it comes up and locks onto the flattop receiver.  

The RAS II will only work with a flattop receiver.  If you have an A2, you will have to use a free float RAS, which requires gunsmithing, or use a ARMS #51 SIR which does not require smithing.

Any of those Knight's systems will run you between $300 and $350.  The SIRs will run you between $350 and $400.

US Forces use both the RAS and the SIR.