Muzzle brake technical part 3D model is available on CGTrader for $12. Original author: izydor-template.
STL (Stereolithography, filesize: 16.6 MB), OBJ (OBJ, filesize: 13 MB), SKP (Sketchup, filesize: 6.24 MB), 3DM (Rhinoceros 3D, filesize: 16.6 MB), 3DS (3D Studio, filesize: 16.6 MB), FBX (Autodesk FBX, filesize: 16.6 MB), STP (STEP, filesize: 16.6 MB)