I have a carbine length AR. It has the round handguards and I want to change to triangular, like the early versions found on the rifles. I have found a set, but what I need is a set of the triangular guards that will use the "round" end cap. The reason is that mine has a 11.5" barrel with a 5" flash suppressor that is pinned/welded on, so I would like to be able to just swap hand guards. Does anyone know of a brand/set that utilizes the round end cap? Thanks in advance.