Here is the final version of the USP-S. It comes in 2 pieces. If it does not fit your priner's dimensions you can easily cut it with Windows 3D builder if you have windows 10 or Meshmixer if you don't. The supressor is twist-on due to its oval tip. Don't overdo the twist though as it will likely wear it out.
pistol1.stl | 955.9KB | |
supressor.stl | 205.4KB |