Stoner 63A Rifle Low-poly 3D model is available on CGTrader for $39. Original author: luchadordev. Specs: 37635 polys, 19701 verts.
OBJ (OBJ, filesize: 170 MB), SPP (Substance Painter, filesize: 805 MB), TEXTURES (Textures, filesize: 224 MB), MAX (Autodesk 3ds Max, filesize: 84.8 MB), FBX (Autodesk FBX, filesize: 84.8 MB), TBSCENE (Marmoset Toolbag, filesize: 84.8 MB)