Either try reinstalling or manually opening the .zip file download and go to it's texture folder, then weapons, and find 1stpersonsniperrifle.dds. Once you find this, copy the file to your desktop and rename it sniperrifle.dds and put it back in the mod's weapons folder you got the other one out of. This fix works with any mod and you can also copy the bump texture too. The bump texture always has a _n after it's name.