Nagpur: The 155x52 mm advanced towed artillery gun system (ATAGS), claimed to have the world’s longest range of 48km, suffered a barrel burst during trials last week. Now, concerns have been raised that the method of firing the ammunition used at present may affect the gun’s performance.

The guns have been made by Bharat Forge and Tata Power, and were being tested with shells made by Ordnance Factory Board (OFB) at the Pokhran range when the accident took place. An investigation is underway in the matter.

To achieve a higher range, a shell has to be fired with extra charge or explosive. In ATAGS, the shell was fired with seven charge modules. Higher charge increases the pressure, which, beyond a certain limit, can affect the shell’s movement. This can lead to accidents like barrel hit, said sources.

It is learnt that concerns were raised about the safety of firing the shells with higher charge a few days before the accident. The OFB, which makes the shell, refused to comment on the issue.

The ATAGS has been designed by Pune’s Armament Research and Development Establishment (ARDE), a unit of Defence Research and Development Organization (DRDO). The gun made by Tata Power suffered the barrel hit. The barrel in both Tata and Bharat Forge guns have been made by the latter.

The ATAGS is designed to achieve a range of 42km and beyond. In 2017, it had achieved a record range of 48km.

The shells for 155mm calibre howitzers made by the ordnance factory are designed to be fired with up to six charge modules and handle pressure up to 340 megapascals. To make the shell fly over 40km, seven charge modules are used. The OFB shells are made under transfer of technology (TOT) from South African company Dennel. Even in the TOT, it has been specified that the gun can handle service pressure of 340 megapascals, or six charge modules at the most.

This is called zone 6 ammunition, and what has been used in ATAGS was zone 7. Higher pressure due to zone 7 can lead to risks. Zone 6 is the standard world over, the sources said.

OFB only makes zone 6 ammunition, which is in line with NATO standards. Even the 155x52 calibre mounted gun system developed by the OFB uses zone 6, a source said.

An official in one of the private companies confirmed that the shell was fired with zone 7 ammunition to achieve a higher charge, and rejected any claim that they had received any warning. So far, both Bharat Forge and Tata guns have fired over 1,000 rounds using the zone 7 rounds. The ATAGS barrel is designed to handle 440 megapascals of pressure.

“The pressure handling capacity is basically meant for the barrel but even the shell is expected to withstand similar levels,” the source said. A final investigation into the incident will only reveal the truth said the company official.

OFB Dropped As Integrator

Earlier, the OFB was supposed to be the lead integrator of the gun, but eventually ARDE tied up with private companies. Sources involved in the development said OFB had also made a prototype barrel for ATAGS. However, later it was not roped in for the project. The details of the present gun were also not shared due to a non-disclosure agreement with the private companies.