Check out Trijicon SRO and 45 Degree Mount Low-poly 3D model on CGTrader for $45. High-quality mesh by SilentSymmetry: 9761 polys, 5393 vertices. PBR, Textured, UV Mapped.
BLEND (Blender, filesize: 57.8 MB), OBJ (OBJ, filesize: 911 KB), FBX (Autodesk FBX, filesize: 59.8 MB), PNG (PNG, filesize: 96.8 MB)