1. Open the program OpenIV.
2. Drag and drop the files within this folder to:
Grand Theft Auto V\update\x64\dlcpacks\mpgunrunning\dlc.rpf/x64/models/cdimages/mpgunrunning_male.rpf/mp_m_freemode_01_mp_m_gunrunning_01

PS~ This model was made by [-CREATIONS-]