The U.S. Army is using over half a million 30mm cannon rounds a year for its AH-64 Apache helicopter gunships. Each round costs over $100. In Iraq and Afghanistan, the most accurate cannon fire comes from the 30mm autocannon on the AH-64 helicopter, and such support is very popular. This is partly because of the increased emphasis on reducing civilian casualties. During the heaviest combat in Iraq (2006-7), about a quarter of the army's 24 AH-64 battalion (18 Apaches each) are there or in Iraq or Afghanistan at any given time, but now these gunships are being shifted from Iraq to Afghanistan. .
The 127 pound M230 30mm cannon fires about ten rounds a second, and AH-64s normally carry 1,200 rounds. The most common round used is the HEDP (high explosive dual purpose), meaning that he round not only penetrates up to 50mm of armor, but generates fragments that kill or wound personnel within four meters (12 feet) of detonation. Each round carries .76 ounces of explosives, is 7.8 inches (20 cm) long and weighs 11.8 ounces (339 grams), while the projectile weighs half a pound (229 grams). A direct hit on a person is fatal, and messy.
Effective range of the 30mm cannon is about 4,000 meters. Time in flight to 3,000 meters is 12 seconds. The fire control system takes care of all the necessary aiming adjustments for long range shots. The Apache also has a red-dot laser indicator for the 30mm cannon. This reduces friendly fire incidents. When in doubt, the AH-64 gunner can flip on the red-dot and ask the guys down below if the right target is about to be hit. The red-dot also has an intimidating effect on the enemy, if you are trying to induce them to surrender.
The biggest problem has been maintenance. The electronics in the AH-64 are particularly time consuming to keep going. So by adopting high altitude tactics, there is less battle damage, and less stress from the violent maneuvering encountered when flying close to the ground. The Apaches still go low, but only when the occasion demands it. Otherwise, they are more useful up high, using their sensors, which, with the magnification on, can show them individuals carrying weapons down there.
In the next few years, all Apaches will be equipped with communications gear that will allow the real-time exchange of video, and other sensor data. Not just with other Apaches, but with air force warplanes and ground troops. But the sensors are all about finding targets for the highly accurate, and lethal, 30mm cannon.