To install with OpenIV you replace the provided 
w_pi_sns_pistol files here:
 
GtaV\mods\update\x64\dlcpacks\patchday8ng\dlc.rpf\x64\models\cdimages\weapons.rpf
GtaV\mods\x64w.rpf\dlcpacks\mpbeach\dlc.rpf\x64\models\cdimages\weapons.rpf

And w_pi_sns_pistol_luxe files go here:

GtaV\mods\update\x64\dlcpacks\mplowrider\dlc.rpf\x64\models\cdimages\weapons.rpf
GtaV\mods\update\x64\dlcpacks\patchday8ng\dlc.rpf\x64\models\cdimages\weapons.rpf


 Thanks for downloading.