To obtain 100.0% accuracy on any level, have the "Unlimited grenades" cheat unlocked and enabled. When you encounter enemies, throw lots of grenades at them and hide. When all the grenades have blown up, check to make sure that there are no enemies remaining. If there are, kill them with a rifle to keep your accuracy high. When you have killed about thirty enemies with grenades, you should have 100.0% accuracy. It should remain that way. If it does not, repeat the process.
It will only work if you select the Difficulty Hardened or Veteran. Once you do this, your original save will be no more. It will not work on Green.
Press X, Triangle, Up, Left,Square at the start menu.
This trick only works with a scoped rifle. Take out the scoped rifle. Walk over a gun that you do not already have. Press L + Right then repeat once. You should now have three weapons. This can be repeated as many times as desired.
Successfully complete the game under the Green difficultysetting to unlock this cheat for the Tour of Duty that was played.Alternately, successfully complete the game with all Bronze medals.