Dave,
A VERY good effort for your first military model.
The Loader's MG is mounted on a Steel Scate Rail (the curved flat piece raised slightly off the turret), which should be a bright steel finish (pictures from Prime Portal):
To make the Mobility Equipment Research & Design Command (MERDC) style camo pattern more accurate, you need more of the tan and black stripes in the pattern.
MERDC 
But, these are only to help you improve. You have done quite well as it is!