20mm Ares (Iaa)

The ARES 20mm, by Jim Frigiola Probably no country has had a larger number of different types of 20mm ammunition in service than the United States. 20mm guns appeared just before WW II primarily for aircraft or anti-aircraft use, most of them originating in Europe from Hispano-Suiza and Oerlikon, and several were pressed into service by US military components causing considerable logistic difficulty and confusion to users in the field. It wasn’t until the 1950’s that the M50 series, the so-called Vulcan rounds, were adopted and these are most common today. By the 1960’s there were at least five different case types that had been used in various service applications at one time or another. In some cases there were both percussion and electric primers used in the same case type thereby causing further interchangeability complications. It was a logistic nightmare. It should come as no surprise then that yet another little-known 20mm variant was developed in the late 1970’s, albeit for export purposes, known as the AR 20. The

AR 20 was a developmental project carried out by Ares Inc. that lasted only a few short years before quietly fading away without ever being fielded. ARES Inc. is a small company founded by Eugene Stoner specializing in R&D work in the area of small arms and advanced gun weapon systems. During the late 1970s ARES, in cooperation with PDA Inc., undertook a project to develop a 20mm air defense weapon system using improved 20mm ammunition referred to as 20mm AR. Funding for the

Left: The percussion-primed 20mm AR TP-T round on left, shown with an electrically-primed M246 HEIT-SD round, is readily identified by its longer projectile and nylon rotating band Right: Shown here is the 20 AR HEIT-SD projectile with elongated fuze on left and an M50-series HEI projectile with M505 fuze on right. Below: Ammunition for the prototype ARES 20mm automatic cannon was handled in 10-round strips

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IAA Journal Issue 498, July/Aug. ’14

Above: This table from an ARES technical report compares the 20mm ARES HEITSD and TP-T projectiles with the older M246 HEIT-SD

Right: The proposed APDS-T projectile is compared to other standard 20mm API and APDS projectiles in this table from an ARES report.

IAA Journal Issue 498, July/Aug. ’14

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AR 20 was provided by an oil-producing Middle Eastern country. Due to unfavorable political events the flow of funding was prematurely cut off before completion of the development program. Neither the ARES gun nor the 20mm AR improved ammunition was ever fielded or produced in any quantity. The little-known ARES 20mm AR round used standard 20x103mm (Vulcan) M103 brass cases with an elongated low-drag projectile. Unlike the standard service US 20mm M50-series aircraft ammunition which is electrically primed the 20mm AR was percussion primed. In addition the projectiles had a nylon rotating band. Due to a greater overall length of about 0.6 inches and its non-electric priming the 20mm AR cannot be considered as M50-series ammunition.

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Little is known about the highrate ARES 20mm self-powered automatic cannon, designed by Eugene Stoner, shown here.

IAA Journal Issue 498, July/Aug. ’14

The ARES 20mm system was an improved air defense system using single-barrel, self-powered, high-rate automatic cannons. The primary round of the associated ammunition family was a High Explosive Incendiary Tracer with Self Destruction (HEIT-SD). Available technical data compares this round to the standard M246 HEIT-SD as used in the Vulcan Air Defense System (VADS). Projectile weight was 91 grams and muzzle velocity was 3585 ft/sec. The ARES round offered improved ballistic performance having 195 ft/sec higher muzzle velocity than the M246, shorter time of flight and improved fuze function sensitivity while operating at lower peak chamber pressure. The low-drag projectile gave substantially higher retained velocity down range. These features resulted in extended range and higher hit probability in the air defense role. The nose fuze for this round had a delay function and was based on an elongated M505-type fuze without a nose cap. Target Practice (TP) and Target Practice-Tracer (TP-T) rounds were loaded and used for gun development and testing purposes. In addition, the ammunition family was to include Incendiary Tracer (I-T) and Armor Piercing Discarding Sabot with Tracer (APDS-T) variants although it is unclear whether either of these two types was ever fabricated. Technical information and some photos for this article were provided by Mr. Herb Roder of ARES Inc.

IAA Journal Issue 498, July/Aug. ’14

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