In addition to the Omega, there are also rails from Midwest and Troy that don't require removal of the front sight/ gas block for installation. The carbine length rail is 7". If you're using the Troy or Midwest Rails you'll have to remove the handguards (pull back HARD on the delta ring, the handguards seperate into bottom and top halves, slip the back out first then the front will just pull back and off) and cut off the delta ring, weld spring and c-clip. It takes about a half hour and all you'll need is a Dremel. Another advantage of the free float rail is that you get a full length top rail to work with for optics, etc.