Navigate to: mods\update\x64\dlcpacks\patchday8ng\dlc.rpf\x64\models\cdimages\weapons.rpf\

Then, drag and drop w_pi_heavypistol.ytd

This is a texture mod, use this link to download the original model by Sxprk: https://www.gta5-mods.com/weapons/smith-wesson-1911