To install with OpenIV you replace the provided heavypistol_luxe and heavypistol_luxe_mag files in these two places: 
GtaV\mods\update\x64\dlcpacks\mpluxe\dlc.rpf\x64\models\cdimages\weapons.rpf
GtaV\mods\update\x64\dlcpacks\patchday8ng\dlc.rpf\x64\models\cdimages\weapons.rpf

Optional .meta's for realistic fire rate and magazine capacity go in these two places: 
GtaV\mods\update\update.rpf\dlc_patch\mpbusiness\common\data\ai
GtaV\mods\x64w.rpf\dlcpacks\mpbusiness\dlc.rpf\common\data\ai

Thanks for downloading.