Lt. Gen. Raymond T. Odierno , the No. 2 U.S. commander in Iraq , said that over a recent 15-day period , volunteers had provided tips that allowed the recovery of a " staggering " amount of munitions : 37,000 pounds of explosives , 2,000 artillery rounds , 500 rockets , nearly 500 armor-piercing projectiles and components , and hundreds of rifles , grenades and suicide vests .