Sawed-off 870

Sawed-off Remington 870

Model, UV, bake - cR45h
Textures, conversion, shell - Millenia
Animations - defaults (Valve/Hidden Path Entertainment)

How to install:

At the moment of release the beta doesn't support modding directly,
so installation can be a bit tricky and you'll need to edit
pak01_dir.vpk every time Valve/HPE releases a patch that updates that file. 
This'll probably change at launch/sometime after launch.

1) unarchive the materials & models folders into 
steamapps/common/Counter-Strike Global Offensive/csgo/
2) BACK UP PAK01_DIR.VPK IN CASE YOU SCREW SOMETHING UP!
3) open up pak01_dir.vpk in Notepad++ or some other proper editor 
(Regular notepad will probably break your pak01_dir.vpk, so don't use that)
4) Use find & replace to find all instances of shot_sawedoff
and replace those with anything else, say, shot_sawedofe for ease. 
What this does is basically it points the VPK to a file that 
doesn't exist, and forces it to load loose files - ie. new models/textures.
5) Go in game and enjoy!    

How to uninstall:

Restore backed-up pak01_dir.vpk. You can delete models/weapons/
v & w shot_sawedoff* and
models/textures/Millenia/Crash_870SO, if you so wish. Not necessary, tho.