I doubt the end caps would offer much protection. Good for stopping birds nesting in the barrel on exercise, but that's about it basically
I'm not certain how this container would have been configured with a large support weapon. Modern CSPEP allow the drop rope to be attached to either side of the container. If the weapon is then strapped vertically to the same side, to facilitate movement in the aircraft and during exit, the container will rotate through 90 degrees when lowered putting the weapon across the top of the bundle to protect it as the container hits the ground.
Graham