Based on the well known AkS 74 U Russian Assault rifle with a futuristic accent.
the gun is about 12K tris in total, modeled using blender and then textured with substance painter, with 4k Textures for the main gun and two 1k texture sets for the magazine and the holosight.
The final images were rendered using blender 2.8 with EEVEE.
AKS 74U