Ballistic Armaments

From Gineipaedia, the Legend of Galactic Heroes wiki

Ballistic armaments were the least-common form of weaponry in use by the final years of the Alliance-Imperial War. Due to the risk involved with firing projectiles in pressurized environments, they were primarily used for ship-to-ship combat and were not scaled down for handheld use the same way beam weapons were. (Legend of Galactic Heroes Volume 3: Endurance)