The U.S. Marine Corps wants gunships, having noted the success of the U.S. Air Force AC-130 aircraft. But they can't afford them, as an AC-130 costs more than three times as much an a marine KC-130J aerial refueling aircraft. But the marines believe they have a solution. The KC-130J is the latest, and largest, USMC version of the C-130 transport used for aerial refueling. But the KC-130J can also carry cargo, and weapons (bombs and missiles) hung from the wings. Thus the proposal is to modify a KC-130J so that it can carry a targeting pod, with the data going to a special cargo container containing control equipment (computers, commo and displays) enabling operators use the day/night sensors of the targeting pod, and release smart bombs (like the 250 pound SDB) and missiles (like Maverick or Hellfire) hung from the wings. A 30mm Bushmaster cannon, mounted on a pallet, could also be loaded, with the rear ramp open, so that there would be gunfire support as well.
The Mk44 30mm Bushmaster cannon weighs 344 pounds and fires at 200 or 400 rounds per minute (up to 7 per second). The cannon has 160 rounds available, before needing a reload. That means the gunner has 25-50 seconds worth of ammo, depending on rate of fire used. Each 30mm round weighs about 25 ounces (depending on type.) The anti-armor shell weighs about half a pound. The armor piercing round will go through 25mm of steel at 2,000 meters range. This will get through the top armor of most vehicles, or the roof of any building, and spray the inside with fragments. At that range, time of flight is about 1.7 seconds. Explosive anti-personnel rounds are also available. From higher altitudes (up to 6,000 meters), the AC-130 fire control system and night vision sensors, enable the 30mm gunners to accurately hit targets with high explosive shells.
Existing AC-130 gunships are armed with a 105mm howitzer, a 25mm and 40mm automatic cannon. But these guns are being phased out of military service. The air force is considering equipping its gunships with smart bombs and missiles.