Sci -Fi rifle made using Blender 2.8. Pictures rendered with latest version of Cycles renderer. The textures used are extremely simple: some emissions, some metallics, and then a small setup using color ramps and a musgrave texture to get the camo look. it isn't the most low-poly thing out there, but it works in UE4 and can be used as a fps weapon. The sight/scope mounted on top may need some work if you want to see through it better, but it works fine if you have refraction enabled. (It isn't a sniper, really just a typical futuristic rifle). You can also just remove the little screen I put into the scope to make it easier.
BLEND (Blender, filesize: 1.25 MB), OBJ (OBJ, filesize: 691 KB), FBX (Autodesk FBX, filesize: 278 KB), STL (Stereolithography, filesize: 577 KB)