https://gamesartist.co.uk/spr300-rifle/
3D Artist Mattias Holsti has used his hard surface modelling techniques to build this realistic SPR300 Rifle, in this article, he talks about, goals, software, references, modelling, UVs, baking, texturing and rendering.
https://www.artstation.com/mattias_h
https://www.artstation.com/artwork/qQXJx2