For years now, the U.S. military has been pondering how to replace its mainstay M16/M4 rifles. The rifles can trace their development history to the years before the Vietnam War. However, the recent conflicts in Iraq and Afghanistan, where engagement distances have been exceeding the effective range of the M16/M4, have brought a renewed purpose in the quest for a replacement. Meet, then, the Next Generation Squad Weapon (NGSW).

“This is a weapon that could defeat any body armor, any planned body armor that we know of in the future,” said General Mark Milley, the current Army Chief of Staff and the next Chief of the Joint Chiefs of Staff, to the Military Times.

The NGSW is still under development. The initial bunch of prototypes is expected to reach selected units in the early summer of 2019. And by 2022, every unit in the U.S. Army is expected to be carrying the new rifle — although the United States Marine Corps (USMC) hasn’t declared an official interest for the new rifle, Marines have been providing feedback to the development team. The NGSW will be fielding the 6.8mm cartridge. Additionally, it will be equipped with a sophisticated night vision targeting system — it’s unclear which, however. Initially, the new weapon is expected to complement not replace the M16/M4.

“This is a weapon that can go out at ranges that are unknown today and that you can see accurately,” added General Milley. He went on to say that the target acquisition system that will be built in the new rifle will surpass any preexisting technology. And it’s also supposed to be very resilient. “It will stand all the rigors of weather, terrain, and soldier use, and all of that kind of stuff. This is a pretty impressive gun,” added General Milley.

The 6.8mm calibre wasn’t picked out of the blue. Comprehensive testing and evaluations by units and departments, to include the U.S. Special Operations Command (USSOCOM), the Army Marksmanship Unit (AMU), and the Army Armament Research, Development, and Engineering Center (ARDEC), testified of the calibre’s accuracy and penetration capabilities.

The M16/M4 and their 5.56mm calibre ammunition originated from a desire for a lightweight weapon following the Korean War. The assumption was that a lighter weapon would enable troops to carry more rounds and be more flexible on the battlefield. Additionally, as a high velocity round, the 5.56mm was deemed more accurate and effective than other competing calibres, such as the 6.8mm and 7.62mm.