Soon after India's ATAGS shoots the longest range, a US gun beats it

Last September, the Kalyani Group and Tata Power (Strategic Engineering Division) claimed world records by firing their in-development artillery guns to a distance of over 47 km. Their Advanced Towed Artillery Gun System (ATAGS) comfortably surpassed the maximum ranges of 40-45 km, currently achieved by similar 155-millimetre, 52-calibre guns in service worldwide.

However, a new American artillery gun is comfortably surpassing ATAGS. Also known by an acronym, the Extended Range Cannon Artillery (ERCA) has achieved a mind-boggling range of 62 km. That doubles the range of the gun the ERCA is based on - the M777 ultra-light towed howitzer that will soon enter service with the Indian Army.

“We just doubled the range of our artillery at Yuma Proving Ground,” General John Murray, who heads the Army Futures Command, stated at the recent Association of the United States Army Annual Symposium, says Fox News.

Artillery guns are judged by three attributes - range, accuracy and consistency. Longer range allows guns to fire from "standoff ranges", beyond the reach of enemy artillery. That is like a boxer with very long arms, pummelling an opponent, whose shorter arms cannot reach one's chin.

Artillery guns with longer range can also engage larger areas from a "gun position", reducing the need to keep redeploying (or shifting) gun positions as the battle lines shift.

 “The Russian and Chinese have been able to outrange most of our systems," Murray said. Now the ERCA is aimed at "regaining tactical overmatch", or outranging the adversaries' artillery.

Interestingly, both the Indian ATAGS and the American ERCA are following broadly the same approach towards extending range. Both are using larger propellant charges to fire the warhead a longer distance. Simultaneously, both are incorporating longer barrels - a time-tested way to increase range.

The ATAGS incorporates a 25-litre chamber, which holds more propellant that the 23-litre chambers in most contemporary 155-millimetre guns, such as the French Nexter and Israeli Elbit guns the Indian army has evaluated. The extra two litres of high explosive propellant shoots out the warhead further.

Like the ATAGS, the ERCA's larger chamber allows for larger propellant charges. According to public statements from the US Army Armament Research, Development and Engineering Center, they have for the first time used "Zone 6" propellant, which is more voluminous than the "Zone 5" top charge they ever fired earlier. In addition, the ERCA's developers extended its barrel length by six feet. Along with the larger chamber, this is said to have extended the gun's range by several kilometres. The challenge in making such enhancements is to strengthen the gun to absorb the higher "shock of firing", without making the gun unacceptably heavy. The ATAGS has had mixed results - it weighs about 17 tonnes, while comparable guns worldwide weigh about 14-15 tonnes. In contrast, the ERCA's enhancements have increased its weight by just 500 kg.

While the ATAGS' higher weight makes the gun less mobile, the army acknowledges that it has also brought several major advantages. It is the world's first gun with an "all-electric drive" that replaces the relatively unreliable hydraulic drives traditionally fitted in towed guns. 

The ATAGS' all-electric drive operates all its gun controls, ammunition handling, opening and closing the breech, and ramming the round into the chamber. This makes firing faster and easier.

In addition, the ATAGS has a six-round "automated magazine" — another global first — that fires a six-round burst in just 30 seconds. Most other existing 155-millimetre, 52-calibre guns in service have three-round magazines. A six-round burst causes more enemy casualties, since all those rounds come down in quick succession, catching soldiers in the open before they can take shelter in their trenches or bunkers.

 Reflecting official confidence in the ATAGS, the two prototypes were paraded on Republic Day in New Delhi this year.

 After development and firing trials are successfully concluded, the Army is likely to procure at least 2,000 ATAGS to make up a serious shortage of artillery. At an estimated Rs 150-200 million apiece, that will result in Rs 300-400 billion worth of business for Indian defence industry, including for many private defence firms.