I WAS EXPECTING AN EARTH-SHATTERING KABOOM: The Ground-Shaking Power of the M777A2 Howitzer. “The M777 Lightweight Towed Howitzer is the most recent 155 mm howitzer, debuting in 2005. The model used here, the A2, has additional software upgrades that allow it to use Excalibur GPS-guided rounds, making the M77A2 incredibly accurate from up to 25 miles away. (For comparison, the gun it replaced, the M198 howitzer, had an effective range of 14 miles, or just under 20 miles if using rocket-assisted artillery rounds.)”