The weapon you want modded is from the base game of fallout 4. Considering the fallout 4 base game is defaulted as the first dlc/mod in the load order you would put '00'. If you took a mod for a dlc you just installed, then the dlc would fall unde

4 4 DLCworkshop02.esm 5 5 DLCworkshop03.esm 6 6 DLCNukaWorld.esm 7 7 Unofficial Fallout 4 Patch.esp 8 8 HUDFramework.esm 9 9 SimSettlements.esm 10 a ArmorKeywords.esm 11 b Homemaker.esm (disabled) More Where That Came From Diamond City.esp 12 c FO4Hotkeys

Complete Modlist and Load Order Guide for Best Fallout 4 Modding Experience. Extreme Fallout 4 Engine & Textures Mods Optimization.