I own a RIS Rail System.  When my barrel gets hot.  IT seems that I can change my POI a couple of inches when shooting from the 50 by pulling on the V grip.  I am using the unit on a2 Colt LW 16" Barrel.  I also own a Bushmaster Dissipator.  Does any Know if the new rifle free float rail system from knights will work on my DISSy.  I spoke with BM and Knights One says  MAybe not sure and the other no. BM seems to think that it should fit over the internal gas block but?  Anyone played around with this?  If I cant get a rail System for my Dissy, what is best for my Carbine?   Thanks

Any or them will work and correct your problem.  FF RAS, RAS 2, SIR will all get it done.

I believe any of them will work too. The full length SIR for your Dissy has not been released yet to my knowledge.

Well i belive i will get the Knights RASII for my Carbine just based on the fact that its about $110.00 cheaper than the SIR and it comes with hand Guards.   But I am still unclear if the Knights Rifle free float unit (RAS/long?) will slide over the internal gas block of the diss without removal?  anyone Installed the free float unit?

The sleeve will slide over BUT the gas block must be removed to install the barrel nut that replaces the factory barrel nut that the sleeve screws onto.  The FF RAS is cheaper than the RAS 2 even if you pay to have the FF RAS installed by a gunsmith.