I emailed Spalah Models and got a reply the next day overnight.
Unfortunately, the rifle is not a separate part of the set — it’s printed together with the figure’s body, since this is not a fictional design, but a 3D scan of a real Ukrainian Special Operations Forces soldier in his personal gear. For the same reason, we do not offer optional weapon replacements. --Spalah Models
Spalah Models also sent a photo.
Since it is a 3D scan of a real Ukrainian SOF, it doesn’t suit what I wanted it for so I’m going to have to pass. 
Thank you to all those who have replied to my question.