The 2012 CCRC submission was based on the rifle inflicting the burn marks. Minus the silencer.
It was, but to confirm this theory, more tests were needed. The CCRC kept Bamber in on a technicality. They dismissed the entire evidence from homicide forensic experts regarding Sheila, without countering it, purely because more tests were needed regarding Nevill's back.
Fast foward and now it can be shown that the Aga parts are a near perfect match for marks on Nevill's back. Maybe they will ask for more tests again.