Installation: 

1) Open OpenIV 

2) Navigate to: 

"GTAV/update/x64/dlcpack/patchday3ng/dlc.rpf/x64/models/cdimages/weapons.rpf" 


3) Replace both OR Rename the original files: 

I.E	"w_me_hammer-ORIGINAL.ydr" and "w_me_hammer-ORIGINAL.ydt" 


4) Drag the files from the download in to OpenIV 

5) Save and Close 

6) Select Hammer in game. 