All Files have the outline as a separate line from the rest of the design, so you will be able to cut out the gun.
The P90 and Tac shotgun do not have color layers when downloaded (my bad), just remember to select the correct lines to cut when cutting.
Other than that Enjoy!
I downloaded a picture of the Fortnite guns from their sides then traced them manually using inkscape. If you plan on doing something similar, trace the outline in one go so it will export as its own layer.