After you have disabled the antenna and picked the lock to enter the building, open the door directly in front of you, Pick up all three Wall Mines downstairs. You will also need all the Frag Grenades to kill Grinko easily. Collect and save them carefully. At the endgame, you are in the barn just before you meet the hostages. Set up booby traps with the three Wall Mines: Put one on the wall behind the left entrance, another one on the left white separator wall facing the hostages (in the middle of the barn), and the last one on the separator wall first half through the aisle that leads to the door to the American hostages. Set up the Wall Mines in the reverse order just described, since you still have to move back to the middle isle to disable the turrets. After you talk to the Chinese, you can take a nice comfortable sniper position in front of the middle aisle; everyone trying to kill the Americans on your right will be blown up.