To install with OpenIV you replace the provided 
w_pi_vintage_pistol files in these two places:
 
GtaV\mods\update\x64\dlcpacks\patchday8ng\dlc.rpf\x64\models\cdimages\weapons.rpf
GtaV\mods\x64w.rpf\dlcpacks\mphipster\dlc.rpf\x64\models\cdimages\weapons.rpf



Weaponvintagepistol.meta and weaponcomponents.meta go here:

GtaV\mods\update\update.rpf\dlc_patch\mphipster\common\data\ai
GtaV\mods\x64w.rpf\dlcpacks\mphipster\dlc.rpf\common\data\ai






 Thanks for downloading.