You may modify and create derivations of these files as long as it credits me for the original work in your release.
These are the source (pre-compile) model files (.smd) and compiling scripts for my L4D2 add-on, SW 5906 x1 & x2.
These are the version 1.0b files of my add-on. If you re-use my animations, know that the left-thumb helper-bone is out-of-whack in these particular files.
For modelers that want to know how L4D2 weapon models are compiled without the usual bugs, such as animations being mismatched online when you're not the host. Also eliminates the need to modify the survivor arms viewmodel just for your weapon.
This also includes the unwrapped wireframes if you just want to texture-mod my add-on very heavily.
Notes: I don't recommend using a custom skeleton for your own models because you will no longer be compatible with custom survivors that change the arms.
The default skeleton is good enough for every movement, just constrain it to a proper animation rig.
Weapon bones can be 100% custom since the arms models don't animate anything off those, of course.
If you want to make a custom weapon that re-uses the original weapon's animations, you can do that too. To do this, you make a copy of the original weapons mdl file, just the mdl file. Change its name by one character, the file name AND the name inside the mdl (with notepad++ or a similar text editor). I'm not sure if the single character thing is required though as I've seen other mods break this rule, as well as not renaming its name within the file, you're welcome to explore this. When you have this, delete all sequences and animations from the qc and use $includemodel "[that mdl file's path in your vpk]".