Installation: 
First  install Jridah's "Springfield 1911 MilSpec SS" model from:
https://www.gta5-mods.com/weapons/colt-1911-animated

Then add my texture files "w_pi_heavypistol.ytd" & "w_pi_heavypistol_mag1.ytd" to it, by:
Going to Grand Theft Auto V\(Mods)\update\x64\dlcpacks\patchday3ng\dlc.rpf\x64\models\cdimages\weapons.rpf\ and replace the files there, that's it! :-)