I have been asking several questions about rail as of late. I have a couple of colt 6920's. I have put enough rounds down range now to know roughly what I am looking for. And roughly what I need or think I need. I have plans to take one of them to a carbine class eventually when funds and time permits. Untill then I want to make one of them a HD set up. It will also be used for somewhat rough handling range drills. I want to mount a sling swivle towards the rear near the receiver, as I'm not real fond of the stock swivle on the barrel. I want to mount a light on the ejection port side. I may want to also mount a VFG, though not sure it will be needed. I use somewhat of a magpul style hold on the forgrip. I strongly want to keep the front sight, without modifying it. I also want to fairly easily get to the barrel for cleaning without having to deal with to much extra dissasembly. Free float is neither here nor there for me. All of my shots are within 200 yards, most being under 100. I was strongly looking into a DD RIS 2 and other DD ris similar variants. However I really dont want to have to replace the barrel nut if I dont absolutly have to. I am now considering the KAC RAS rail. I have also looked into the centurian FSP carbine rail. I have to admit parts the military use have a certain cool factor to them. So is the RAS worth it? It seems to meet most of my needs/wants. How solid is it, any movement under some torque? How durable? Same question for the centurian rail? Anything else I should strongly look into?