...I would highly recommend against it. TF2 has a cartoonish aesthetic, and as such it clashes with realistic-looking props. They just don't look right when put into the same picture.

That said, I recommend that you use the existing TF2 Muzzleflash prop that's in the TF2 files instead.

I should also note that the repeated use of these props with TF2 models has prompted me to think about making a Stylized Muzzleflash prop that would fit cartoonish models better. Stay tuned.