BACKUP YOUR ORIGINAL FILES!
Before replacing, make sure to make a backup folder and throw your standard dlc there.
Installation:
1.Open OpenIV,
2.Go to 2.mpgunrunning(MK2) update\x64\dlcpacks\mpgunrunning/x64/models/cdimages/weapons/
2.1.patchday8ng(MK1) update\x64\dlcpacks\patchday8ng/x64/models/cdimages/weapons/
3.Drag everething from downloaded archive and put it in this folder.
4.Enjoy!.
Credits:
Litrium