i am building up my ar15 now. it started life as a dpms oracle. its a 16" carbine length rifle. i love it but i want to start to modify it. the big mod now is the forearm. i am looking at a free float quad rail. here are my questions: 1. it is a carbine length forearm now. am i restricted to putting on a carbine length quad rail or can i put on a longer one if it will fit over the gas block? 2. do i need any special tools to remove the delta ring and put on the free float gear. i have a delta ring tool as well as a generic armorers tool that can be used for a whole bunch of things. as well as a torque wrench since i have gathered the new free float barrell nut has a specific torque spec. 3. any suggestions on what to get? currently looking at a yankee hill machine diamond series rail. know someone who has the same one and he seems to like it.