A rapidly learned in-country skill was knowing from sound what weapon or weapons were being fired and pinpoint the location of the shooter. At night our smaller ammunition fired red tracer rounds while the enemies fired green. Tracers were a nighttime aid that gave mixed results and revealed the shooter’s position. The location from hearing method worked best in open ground. When our 105mm howitzers were shooting, their sound and concussion masked small arms fire. A 105mm shell exiting the gun tube creates MAJOR concussion and one is unlikely to hear or feel small arms fire.