LamboJoe

Okay... Here's what you do: In the middle of the level, next to the tank, there will be a rock. Jutting out from the rock will be a "cliff".
On the side that is closest to the huts, try the best you can to walk up onto the top of the cliff. Now you can enter the rock. The game designers didn't think you'd be able to do this, so they didn't put a "block" there. Once inside the rock, you can shoot people on the outside, while your opponent's bullets harmlessly bounce off the rock you are in. Even better, you can exit the rock and be able to walk in midair, unless you touch something like a tree or another rock. You can even run away from the level itself! There's nothing there, and if you drop a grenade, it will fall and keep falling until it explodes. I recommend using a sniper rifle such as a Mosin-Nagant, Kar 98, Springfield, or the Lee-Einfield. This way, you can move around OUTSIDE of the level and still be able to shoot your opponents from a long distance. I had this same problem, too, but another player showed me how to enter the rock. Happy Hunting! :-)