Curious, was the DD block touching the rail at all times? I have VLTOR clamp with a TRX extreme - while its tight in there, there is enough room.
MrCleanOK.....I don't necessarily agree with your running order there - clamp is often better for the home installer as it negates the need to dimple the barrel as you should with a set screw - putting a set screw on without dimpling is way less effective than clamp. A properly well secured low profile clamp covered by a rail ain't going nowhere.
In addition, clamp is more preferred by the extreme accuracy crowd who sometimes feel the other types can impart stress on the barrel and fubar your harmonics (not that it really matters to most people).
