One of the best all around guns in Combat Arms is the G36E. It takes time to master, but once you are skilled with it the rewards are plenty. Any G36E marksman should be able to take down an opponent at a long range almost if not as fast as someone could with a sniper rifle. - Olah92
My favorite thing about his site? He has a goal to make a video montage for just about every weapon in the game. His compilation of Combat Arms videos is available at olah92.co.nr/ca. Nothing better then some good old double barrel wastage.