Check out PBR Swedish Ak5C and Aimpoint CS Low-poly 3D model on CGTrader for $54. High-quality mesh by steffe-engdahl: 28037 polys, 14864 vertices. PBR, Textured, UV Mapped.
MA (Autodesk Maya, filesize: 4.81 MB), OBJ (OBJ, filesize: 3.11 MB), FBX (Autodesk FBX, filesize: 4.89 MB), DAE (Collada, filesize: 4.98 MB)