During this time the gun was in the prototype phase so most likely it will change a bit. I felt it had a really cool design and I made it using mostly Zmodeller to create the base mesh and Dyanamesh to refine and add details.
I will be creating a course on this process which was inspired by the work Redstorm Entertainment (A subsidiary of Ubisoft) created for "Tom Clancy's Ghost Recon: Future Soldier" and "Tom Clancy's:The Division". They use Zbrush for their weapon modelling.
You can view a Hi-Res version here: https://www.artstation.com/artwork/OP52w