Definitely mod problems

Maybe a mod that alter scopemount?

Thats the thing, I dont now what mod does this.

I'll go out on a limb and day : probably you either have >:3's Russian scopes pack (probably an update of the mode broke the script;removing then reinstalling said mod should fix it) or,you had a custom weapon which received an update to make it compatible with the "custom weapon parts for custom weapons". Again,remove and reinstall the mod

That can be caused by mods that directly edit these type of attachments something that my mods don't touch at all. Post list of mods because without that we can only guessing.

Find the problem

Extra Attachments Compilation