Try this:
1. Install the required version of the mod (currently version 1.1.1f)
2. Unzip the archive and move the folder with the content pack to the "ModularWarfare" folder.
If you are talking about optical sights on snipers, then they will not work on current new versions. The description says to use version 1.1.1f of the mod, then you will not have problems with optics.
But if the problem is different, please describe it specifically.
1. Install the required version of the mod (currently version 1.1.1f)
2. Unzip the archive and move the folder with the content pack to the "ModularWarfare" folder.