stabbyCauses crashes for me in casual now, as well. The file I was using before the installer was a thing still hides the gun (but not gun arm) and is stable to use, though. I can't remember where exactly I clicked to get it, so I'll just reupload it for anyone that needs it:
I couldn't check out what degu uploaded because zippyshare.com wanted me to install something I didn't want to in my browser to download :(
Frankly it's probably just something with how the viewmodel animations are configured in the game itself that causes it to crash with animation files meant for older model versions.
I know how to rewrite the installer to be version (and for that matter, viewmodel mod) agnostic, but it's a lot of effort and I'm not sure if I'll ever spend the time doing it.
If that file still works in casual, it means preloading still works, and it's an issue with the content and not the delivery method, which can be fixed.