THIS IS NOT A SPRITE, THIS IS INDEED, A MODEL.
Last updated 9/29/12. Check the changelog in the RAR file for more detailed information on updates.
HERO LIGHT HAS ASSEMBLED A TEAM AND IS ATTEMPTING TO GET THE MINIGUN AND SENTRY WORKING. BEST OF LUCK TO THEM, THE FINISHED PRODUCT WILL BE LINKED HERE IF THEY SUCCEED!
Wwwaffles321 originally discovered this and uploaded it, however, it got trashed due to people thinking it was a sprite(that and it lacked decent screenshots). I decided to add the beta muzzleflash to other weapons and fix it up on the weapons wwwaffles321 made it for. Currently, this will NOT work for the Minigun or Sentry. It's as if TF2 won't read the edited CTX file for the Minigun when I try(perhaps some kind of anti-cheat measure?).
I will try to keep this up to date with added weapons and upgrades to current weapons.