I am trying to remember here. I had a shock isolated bezel like the C2 bezel for my 6P awhile back. If I remember correctly, the LA (in your case, the drop in) would be suspended in the bezel and not make good contact with the body of the M2. The bezel of the 6P, C2. C3, 9P. the C series Surefires, allow better better body contact with drop in's such as the D26.
Bill
