I tried to get a laser site mod for my weathered 10 mm pistoI from the arms merchant in 188 Trading Post many, many times -- loading an earlier save, exiting from game, etc... When I equip the mod my weapon disappears & I'm holding an invisible gun, & my entire field of vision looks like I'm looking through a pane of frosted glass. I have the pc version. Has anyone else encountered this bug?

I believe this happened because the weathered 10mm pistol in the Classic pack is missing the meshes for it's modified versions. I haven't tried to add any weapon mods to mine so this hasn't happened to me yet. I do believe that there is a mod on the new vegas nexus that fixes this. I think the name of the mod is Weathered 10mm Pistol Fix. Hope this helped you.

you can't mod unique weapons idk why