as @TheOneOfWonders mentioned it, the model is messed up (dark spots where elements should be), also if you plan on porting the animations from TF2C you'll have to convert them so they work with the existing scouts animations (breaking the Soda Popper in the process... So you'll have to eithier hack (=read modify) the SP's model so it doesn't looks like broken or make a FaN with a longer barrel (since the Super Shotgun is basically a FaN with a full length barrel vs a Sawn off barrel)
I've downloaded this to keep it, but there's one real issue with this..
you've broken the fucking model (lever for breaking the barrels is out of place and the "hinges" for the barrel are out of place, obvious by the black holes on the texture implying where those parts should actually be)
Suggestion to improve: use the mercenary's animations for the super shotgun for this, although you'll have to make this also replace the soda popper since it'll break that weapon.