Installation:
To install use open IV and search for w_ar_assaultrifle_smg.ydr. 
Replace the files located in
Grand Theft Auto V\mods\update\x64\dlcpacks\mplowrider2\dlc.rpf\x64\models\cdimages\weapons.rpf\ 
Remember to rebuild archive.

These models were created by Heffy of fallout nv nexus.
Edited by me.  
http://www.nexusmods.com/newvegas/mods/42970/?

thanks:
Heffy for great models. 
Rockstar for great game.
TrophiHunter for youtube channel.  