The M1299 was an American prototype 155 mm self-propelled howitzer developed by BAE Systems beginning in 2019 under the Extended Range Cannon Artillery (ERCA) program. It was based on the M109A7 howitzer and was primarily designed for the purpose of improving the M109's effective range. The program was canceled in 2024.
An Extended Range Cannon Artillery (ERCA) during a test in March 2021, at the U.S. Army Yuma Proving Ground
A XM1113 extended range artillery round, shown here at a range demonstration, uses a rocket-assist motor
155 mm is a NATO-standard artillery shell caliber that is used in many field guns, howitzers, and gun-howitzers. It is defined in AOP-29 part 1 with reference to STANAG 4425.
M107, M795, M483A1 155 mm projectiles
M107 projectile 155 mm projectile being loaded into an M777 howitzer