Serious Firepower! Apache M230 on Ground Vehicles: Better Than the Bushmaster?

 
M230 30mm chain gun on AH-64D. By 100yen CC BY-SA 3.0
 
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The M230, when mounted on Apache gunships, has proven its worth in many theatres of war. This gun has provided unparalleled fire support to ground troops in the global war on terror. Its performance has moved the M230 into the spotlight as a possible lightweight weapon to be mounted on armored vehicles to add an extra degree of heavy firepower.

Having placed the M230 in the spotlight, the question raised is: how does it compare to the 30mm Bushmaster cannon that is currently fitted to armored vehicles?

The M230 was designed explicitly for aerial use, so it uses 30X113 rounds that fit the DEFA and ADEN fighter jet cannons. It also uses a linkless feed as the shells were designed to be mounted upside down on a helicopter.

An M230 Chain Gun mounted on an AH-64 Apache. By Jonathan Mallard CC BY 2.0

Another consideration is that these rounds have a low muzzle velocity. Penetration was never a consideration since aircraft do not carry heavy armor and the explosive capability of the rounds was enough to produce the desired effect.

The muzzle velocity of the M230 round is somewhere in the region of 810 m/s and relies on the small, shaped, high-explosive charge in its nose to defeat the armor it encounters. This design can lessen the explosive filler of the round as a hollow space must be left for the formation of the copper jet with the shaped charge.

High explosive incendiary rounds (HEI) come with safety concerns so, during the global war on terror, the M230 has been equipped with high explosive dual purpose (HEDP) rounds that have worked exceptionally well.

Irish Mowag Piranha shooting Mk44 Bushmaster II. By Irish Defence Forces CC BY 2.0

Once moved to ground operations, the HEDP round will work effectively against soft or lightly armored targets, but the penetration ability of the rounds will prove to be their downfall. The manufacturer, Northrop Grumman, documents their performance at 25mm of Rolled Homogeneous Armor (RHA) at 500 meters at 50 degrees.

This penetration rate would allow penetration of infantry fighting vehicles and some armored personnel carriers but would bounce off heavy infantry fighting vehicles. Slat or spaced armor would also stop penetration due to the shaped charge in the nose as compared to standard anti-personnel rounds that would pass through this type of armor.

AC-130U Spooky Gunship from the 4th Special Operations Squadron jettisons flares over an area near Hurlburt Field, Florida

There is currently a ground equivalent of the M230, known as the M230LF, which has a longer barrel to allow a higher muzzle velocity. As the US military does not an anti-personnel round for this weapon, the additional muzzle capacity will let the cannon to shoot faster and flatter but will not increase its penetration ability.

There are some positives to this technology. The rounds are smaller and lighter which will allow more to be carried, and the additional weight of the weapon system has been minimized.

When moved to a ground mounting, a linked feed had to be introduced with a delinker attached to the cannon which added to the weight of the system, but extra weight was expected due to the longer barrel length. The added complexity of the linked feed is complicated but necessary to accommodate the flexible overhead mounts into which the M230LF has been fitted.

Oshkosh L-ATV fitted with Orbital ATK’s M230 LF 30mm lightweight automatic chain gun mounted on EOS R400S-MK2 remote weapon station. By oshkoshdefense.com
CC BY-SA 4.0

Military sources indicate that the M230LF is to be mounted on the new series of armored vehicles: the MATV (all-terrain vehicles) and the Joint Light Tactical Vehicle (JLTV). This would be a vast improvement over the current CROWS system with its 50mm gun.

The benefit will be slightly diminished by the fact that the ammunition system will take up a lot of space, so it is not likely to be fitted to every vehicle. However, those vehicles to which it is fitted will become highly effective fire support platforms that will have the capability of delivering high explosive rounds over several kilometers.

An Oshkosh M-ATV in July 2011

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The M230LF will not feature the range of rounds found on the Bushmaster system, such as armor-piercing rounds and air-burst rounds.

But as the turret is substantially lighter than that for the Bushmaster, it will give the military a middle ground between the heavy, fully-fledged 30mm cannon system represented by the Bushmaster and the light grenade launching and heavy machine gun systems. This middle ground will prove to be a valuable addition to the US arsenal of ground support systems.