I agree with everyone below. Although the model fits the TF2's cartoon-ish look. Still it looks blocky and never fits as a view model
And as captive said, you'd better re-do this with BrainCollector's remade M4. Here's the model so you won't look so much for it https://gamebanana.com/models/2195 And for better realism you should put the side with the shell ejection port on the right side. You can also edit the textures a bit to give them some cartoon-ish look to fit the other weapons in the game. Good Luck! ;)
As said before, don't use the world model unless you want it to look like a port from something in the late 90's. And if you wanna go the extra mile for authentic assault rifle-ness, shell ejection would make me eject my shells, if you know what I mean~
I'm not sure it's a good idea to using world model of CS:S M4A1, especially since BrainCollector already fix the view model of M4A1, because this is looks blocky and not have much detail on the model. If the purpose is to maintain the frame rate by using low-poly mesh, I think it's not really worth, because the view model of M4A1 is still considered low poly mesh.
This is very good, but I don't understand one thing: M4A1 will be more accurate on SMG, because this version is without suppressor, with suppressor fits more on Cleaner's Carbine, but this is only my opinion.