css_anti-death's_mossberg_hexe by Jason278

This download looks like an addon. You need to extract the downloaded zip and put the addon folder in your Garry's Mod addons folder. You should end up with a directory structure similar to below:

• steamapps
  • common
    • garrysmod
      • garrysmod
        • addons
          • CSS Anti-Death's Mossberg hexed <-- Addon folder!
            • e.g.
            • lua
            • maps
            • materials
            • models
            • etc

• CSS Anti-Death's Mossberg hexed/
  • materials/
    • models/
      • weapons/
        • v_models/
          • ad_mossberg/
            • mossberg.vmt
            • mossberg.vtf
            • mossberg_normal.vtf
        • w_models/
          • ad_mossberg/
            • mossberg.vmt
  • models/
    • Mospons/
      • w_shot_m3super90.dx80.vtx
      • w_shot_m3super90.dx90.vtx
      • w_shot_m3super90.mdl
      • w_shot_m3super90.phy
      • w_shot_m3super90.sw.vtx
      • w_shot_m3super90.vvd
      • w_shot_m3super90.xbox.vtx

Rilli Niga, Fartface206, ashahroz056, RED Floyd /(Weber)\, Jacklivingstone43, Legoben2, Warpath-the-drone swe, Warpath-the-drone swe, Warpath-the-drone swe, Warpath-the-drone swe, Minimole the Lorax, LazerSpy, LazerSpy, andrewdbuilder, andrewdbuilder