“An H&K L30 Gatling laser. Designed specifically for military use, these were in the prototype stage at the beginning of the War. Multiple barrels allow longer firing before overheating. Powered by Micro Fusion Cells.”
Commonly regarded as the ultimate energy weapon, the L30 saw use (post-War) by Brotherhood of Steel Paladins, UnityNightkin and even Enclave soldiers. (On that note, Advanced Power Armors have a 90% resistance against laser damage, which means the user has to rely on critical hits to deal significant damage against Enclave soldiers).