LOL yeah, that was a rack of M-4s with scopes and regular tops. On my right was the rack that had the M240G, and to the left a couple crates of M134 vulcan miniguns, and it was my sorry job to guard them when everyone was gone. Oh and somewhere was a rack of M9s as well.
The G has a pistol grip but no heatshield. I believe the D has the spade grip like the M2. The C is set up to be operated from inside a vehicle/tank- if memory serves. The heatshield on the B is a sound addition to the system, in that it decreases the likelihood of the operator burning him/herself; I would think it would cause the barrel to retain heat however, resulting in reduced barrel life and less flexibility when it comes to changing barrels to prevent stoppages/malfunctions and cook-offs.