Board Thread:Questions and Answers/@comment-121.54.54.249-20140809065344/@comment-209.6.246.62-20140821200007

Preferably the Marksman M1 and upgrading it to the Marksman M2, or getting the Combat Rifle and upgrading it 3 times to get it to the Rambo's Rifle. Upgrading the Elite Rifle 3 times to the S.W.A.T. Rifle also works too, although the other 2 easily out-damage it.